diff --git a/BuildController.gd b/BuildController.gd
index 114575f..1d33801 100644
--- a/BuildController.gd
+++ b/BuildController.gd
@@ -1,5 +1,8 @@
 extends Node2D
 
+const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
 # Space-side building UI. Owns:
 #   - the build menu (place a mothership, ship crafter or command centre)
 #   - the shared ACTION button, which adapts to whatever the fleet is
@@ -22,20 +25,18 @@ extends Node2D
 @onready var building_action_button: IconButton = get_node("../UI/BuildingActionButton")
 
 @onready var build_menu: Control = get_node("../UI/BuildMenu")
-@onready var build_mothership_button: IconButton = get_node("../UI/BuildMenu/MothershipButton")
-@onready var build_crafter_button: IconButton = get_node("../UI/BuildMenu/CrafterButton")
-@onready var build_command_button: IconButton = get_node("../UI/BuildMenu/CommandButton")
 @onready var build_close_button: IconButton = get_node("../UI/BuildMenu/CloseButton")
 @onready var build_status: Label = get_node("../UI/BuildMenu/StatusLabel")
-@onready var build_extractor_button: IconButton = get_node("../UI/BuildMenu/ExtractorButton")
-@onready var build_hub_button: IconButton = get_node("../UI/BuildMenu/TransportHubButton")
-@onready var build_lab_button: IconButton = get_node("../UI/BuildMenu/ShipLabButton")
 @onready var lab_menu: Control = get_node("../UI/LabMenu")
 @onready var lab_vessel_buttons: Array = [
 	get_node("../UI/LabMenu/VesselA"), get_node("../UI/LabMenu/VesselB"),
 	get_node("../UI/LabMenu/VesselC"),
 ]
 @onready var lab_vessel_label: Label = get_node("../UI/LabMenu/VesselLabel")
+@onready var lab_vessel_labels: Array = [
+	get_node("../UI/LabMenu/VesselALabel"), get_node("../UI/LabMenu/VesselBLabel"),
+	get_node("../UI/LabMenu/VesselCLabel"),
+]
 @onready var lab_detail: Label = get_node("../UI/LabMenu/DetailLabel")
 @onready var lab_status: Label = get_node("../UI/LabMenu/StatusLabel")
 @onready var lab_buy_button: IconButton = get_node("../UI/LabMenu/BuyButton")
@@ -78,20 +79,7 @@ extends Node2D
 	get_node("../UI/HangarMenu/FleetShieldLabel"),
 	get_node("../UI/HangarMenu/FleetTransporterLabel"),
 ]
-@onready var build_menu_entries: Array = [
-	[GameState.BUILDING_MOTHERSHIP, build_mothership_button,
-		get_node("../UI/BuildMenu/MothershipLabel"), get_node("../UI/BuildMenu/MothershipCost")],
-	[GameState.BUILDING_SHIP_CRAFTER, build_crafter_button,
-		get_node("../UI/BuildMenu/CrafterLabel"), get_node("../UI/BuildMenu/CrafterCost")],
-	[GameState.BUILDING_COMMAND_CENTER, build_command_button,
-		get_node("../UI/BuildMenu/CommandLabel"), get_node("../UI/BuildMenu/CommandCost")],
-	[GameState.BUILDING_EXTRACTOR, build_extractor_button,
-		get_node("../UI/BuildMenu/ExtractorLabel"), get_node("../UI/BuildMenu/ExtractorCost")],
-	[GameState.BUILDING_TRANSPORT_HUB, build_hub_button,
-		get_node("../UI/BuildMenu/TransportHubLabel"), get_node("../UI/BuildMenu/TransportHubCost")],
-	[GameState.BUILDING_SHIP_LAB, build_lab_button,
-		get_node("../UI/BuildMenu/ShipLabLabel"), get_node("../UI/BuildMenu/ShipLabCost")],
-]
+var build_menu_entries: Array = []
 
 # Which vessel the lab screen is showing, and which visible upgrade card is
 # selected. Each vessel gets its own small set of direct cards; the detail and
@@ -115,6 +103,12 @@ var lab_building_id: int = 0
 @onready var craft_interceptor_label: Label = get_node("../UI/CraftMenu/InterceptorLabel")
 @onready var craft_transporter_label: Label = get_node("../UI/CraftMenu/TransporterLabel")
 @onready var craft_shield_label: Label = get_node("../UI/CraftMenu/ShieldLabel")
+@onready var craft_vessel_buttons: Array = [
+	craft_interceptor_button, craft_shield_button, craft_transporter_button,
+]
+@onready var craft_vessel_labels: Array = [
+	craft_interceptor_label, craft_shield_label, craft_transporter_label,
+]
 
 # --- the transfer panel (#24) ---------------------------------------------
 # Ore used to be moved from inside whichever panel happened to be open: "load
@@ -148,41 +142,6 @@ var lab_building_id: int = 0
 @onready var formation_close_button: IconButton = get_node("../UI/FormationMenu/CloseButton")
 @onready var formation_reset_button: IconButton = get_node("../UI/FormationMenu/ResetButton")
 
-# What each option is and does, shown before anything is spent. Picking a
-# structure is a real commitment - it costs ore, and a mothership placement
-# can destroy the one you already have - so no option builds straight from
-# the menu; each one explains itself first and waits for a confirmation.
-#
-# The bodies are kept short on purpose: at the UI's font size the popup holds
-# roughly eight lines, and a placement condition or a price warning is
-# appended below them and needs some of those lines.
-const BUILDING_INFO: Dictionary = {
-	GameState.BUILDING_MOTHERSHIP: {
-		"title": "Mothership",
-		"body": "Fleet home port. A wiped-out fleet rebuilds here, and extractor haulers deliver ore here.",
-	},
-	GameState.BUILDING_SHIP_CRAFTER: {
-		"title": "Ship Crafter",
-		"body": "Fly the fleet onto it, then use the action button to build extra vessels.",
-	},
-	GameState.BUILDING_COMMAND_CENTER: {
-		"title": "Command Center",
-		"body": "Fly the fleet onto it to drag your fleet into a new formation. Rebuilt fleets keep it.",
-	},
-	GameState.BUILDING_SHIP_LAB: {
-		"title": "Ship Lab",
-		"body": "Fly the fleet onto it to upgrade each vessel type, and to unlock the shield vessel.",
-	},
-	GameState.BUILDING_TRANSPORT_HUB: {
-		"title": "Transport Hub",
-		"body": "Stations transport vessels. They fetch ore from your mothership and deliver it to whichever building is waiting on it.",
-	},
-	GameState.BUILDING_EXTRACTOR: {
-		"title": "Extractor",
-		"body": "Mines a planet and runs a hauler to your mothership. It keeps earning while you are away.",
-	},
-}
-
 # Which structure the popup is currently offering to build, or "" when it is
 # only explaining something that cannot be built right now.
 var pending_build_type: String = ""
@@ -210,13 +169,7 @@ var context_actions_expanded: bool = false
 func _ready() -> void:
 	build_button.pressed.connect(_on_build_pressed)
 	build_close_button.pressed.connect(_close_build_menu)
-	build_mothership_button.pressed.connect(_on_place_mothership)
-	build_crafter_button.pressed.connect(_on_place_crafter)
-	build_command_button.pressed.connect(_on_place_command_center)
-	build_extractor_button.pressed.connect(_on_place_extractor)
-	build_hub_button.pressed.connect(_on_place_transport_hub)
-	build_lab_button.pressed.connect(_on_place_ship_lab)
-	craft_shield_button.pressed.connect(_on_craft_shield)
+	_configure_build_menu_entries()
 	lab_close_button.pressed.connect(func(): lab_menu.visible = false)
 	lab_buy_button.pressed.connect(_on_lab_buy)
 	for i in range(lab_vessel_buttons.size()):
@@ -229,8 +182,9 @@ func _ready() -> void:
 	action_button.pressed.connect(_on_context_action_pressed)
 	building_action_button.pressed.connect(_on_action_pressed)
 
-	craft_interceptor_button.pressed.connect(_on_craft_interceptor)
-	craft_transporter_button.pressed.connect(_on_craft_transporter)
+	for i in range(mini(craft_vessel_buttons.size(), VESSEL_DEFINITIONS.all().size())):
+		var definition: Resource = VESSEL_DEFINITIONS.all()[i]
+		craft_vessel_buttons[i].pressed.connect(_on_craft_vessel.bind(definition.definition_id))
 	craft_close_button.pressed.connect(func(): craft_menu.visible = false)
 
 	transfer_button.pressed.connect(_on_transfer_pressed)
@@ -267,6 +221,21 @@ func _ready() -> void:
 	_layout_context_buttons()
 
 
+func _configure_build_menu_entries() -> void:
+	build_menu_entries.clear()
+	for definition in BUILDING_DEFINITIONS.all():
+		if definition.menu_button_name == "":
+			continue
+		var button: IconButton = get_node("../UI/BuildMenu/%s" % definition.menu_button_name)
+		var label: Label = get_node("../UI/BuildMenu/%s" % definition.menu_label_name)
+		var cost_number: NeonNumber = get_node("../UI/BuildMenu/%s" % definition.menu_cost_name)
+		button.icon = definition.menu_icon
+		button.pressed.connect(_show_building_info.bind(String(definition.definition_id)))
+		label.text = definition.display_name
+		cost_number.amount = definition.cost
+		build_menu_entries.append([definition.definition_id, button, label, cost_number, definition])
+
+
 # True while a building prompt or panel owns the shared action slot, so the
 # enter-atmosphere prompt knows to stay out of the way.
 func is_showing_building_prompt() -> bool:
@@ -318,9 +287,7 @@ func _process(delta: float) -> void:
 	if build_menu.visible:
 		# Keep the greyed state live while the menu is open, so flying onto
 		# a planet lights the option up without reopening it.
-		build_extractor_button.enabled = _planet_under_fleet() != null \
-			and GameState.is_building_unlocked(GameState.BUILDING_EXTRACTOR)
-		build_extractor_button.queue_redraw()
+		_refresh_build_option_states()
 
 	if craft_menu.visible:
 		# Live, so a delivery arriving while the menu is open visibly works
@@ -359,10 +326,7 @@ func _process(delta: float) -> void:
 
 	current_building = pending_building
 	context_actions_expanded = false
-	# The hangar is where finished vessels are delivered (#23), so it belongs
-	# at the mothership and nowhere else.
-	hangar_button.visible = current_building != null \
-		and current_building.building_type == GameState.BUILDING_MOTHERSHIP
+	hangar_button.visible = false
 	# Every building can hold ore, so the transfer button rides alongside the
 	# action button rather than being one of the things the action button
 	# turns into - the two are independent choices at the same structure.
@@ -371,7 +335,7 @@ func _process(delta: float) -> void:
 	action_button.visible = current_building != null
 	if current_building != null:
 		var actions: Array = _context_action_buttons()
-		building_action_button.icon = _action_icon_for(current_building.building_type)
+		building_action_button.icon = int(current_building.definition.action_icon)
 		building_action_button.queue_redraw()
 		action_button.icon = building_action_button.icon if actions.size() == 1 else IconButton.Icon.ACTION_MENU
 		action_button.queue_redraw()
@@ -403,13 +367,20 @@ func _layout_context_buttons() -> void:
 func _context_action_buttons() -> Array:
 	if current_building == null:
 		return []
-	var actions: Array = [transfer_button]
-	if current_building.building_type in [GameState.BUILDING_MOTHERSHIP, GameState.BUILDING_SHIP_CRAFTER,
-			GameState.BUILDING_SHIP_LAB, GameState.BUILDING_COMMAND_CENTER]:
-		actions.push_front(building_action_button)
-	if current_building.building_type == GameState.BUILDING_MOTHERSHIP:
-		actions.append(hangar_button)
-	return actions
+	var buttons: Array = []
+	for action in current_building.available_actions():
+		var button: IconButton = _button_for_building_action(action)
+		if button != null and button not in buttons:
+			buttons.append(button)
+	return buttons
+
+
+func _button_for_building_action(action: String) -> IconButton:
+	if action == "transfer":
+		return transfer_button
+	if action == "hangar":
+		return hangar_button
+	return building_action_button
 
 
 func _on_context_action_pressed() -> void:
@@ -433,20 +404,6 @@ func _collapse_context_actions() -> void:
 	_layout_context_buttons()
 
 
-func _action_icon_for(type: String) -> int:
-	match type:
-		GameState.BUILDING_SHIP_CRAFTER:
-			return IconButton.Icon.SHIP
-		GameState.BUILDING_TRANSPORT_HUB:
-			return IconButton.Icon.TRANSPORT_HUB
-		GameState.BUILDING_SHIP_LAB:
-			return IconButton.Icon.SHIP_LAB
-		GameState.BUILDING_MOTHERSHIP:
-			return IconButton.Icon.MOTHERSHIP
-		_:
-			return IconButton.Icon.COMMAND_CENTER
-
-
 func _check_fleet_wipe() -> void:
 	if not fleet.ships.is_empty():
 		return
@@ -465,11 +422,12 @@ func _on_action_pressed() -> void:
 	for bar in resource_bars:
 		bar.building_id = current_building.building_id
 
-	if current_building.building_type == GameState.BUILDING_MOTHERSHIP:
+	var action: String = current_building.primary_action()
+	if action == "research":
 		skill_menu.visible = true
 		skill_tree.reset_scroll()
 		_refresh_skill_menu()
-	elif current_building.building_type == GameState.BUILDING_SHIP_CRAFTER:
+	elif action == "craft":
 		# Remembered explicitly: _process() clears current_building while any
 		# menu is open, so by the next frame the panel would no longer know
 		# which crafter it belongs to. Losing this line makes every button in
@@ -478,11 +436,11 @@ func _on_action_pressed() -> void:
 		craft_building_id = current_building.building_id
 		craft_menu.visible = true
 		_refresh_craft_status()
-	elif current_building.building_type == GameState.BUILDING_SHIP_LAB:
+	elif action == "lab":
 		lab_building_id = current_building.building_id
 		lab_menu.visible = true
 		_refresh_lab()
-	elif current_building.building_type == GameState.BUILDING_COMMAND_CENTER:
+	elif action == "formation":
 		formation_menu.visible = true
 		formation_editor.queue_redraw()
 
@@ -551,8 +509,7 @@ func _refresh_build_status() -> void:
 	# Researched but not usable right here is still shown, greyed: an
 	# extractor needs a planet under the fleet, which is a "not now" rather
 	# than a "not yet".
-	build_extractor_button.enabled = _planet_under_fleet() != null \
-		and GameState.is_building_unlocked(GameState.BUILDING_EXTRACTOR)
+	_refresh_build_option_states()
 
 	# Prices are shown under each option now, so this only needs to say
 	# whether the fleet is somewhere an extractor could go.
@@ -562,16 +519,14 @@ func _refresh_build_status() -> void:
 		build_status.text = ""
 
 
-func _on_place_mothership() -> void:
-	_show_building_info(GameState.BUILDING_MOTHERSHIP)
-
-
-func _on_place_crafter() -> void:
-	_show_building_info(GameState.BUILDING_SHIP_CRAFTER)
-
-
-func _on_place_command_center() -> void:
-	_show_building_info(GameState.BUILDING_COMMAND_CENTER)
+func _refresh_build_option_states() -> void:
+	for entry in build_menu_entries:
+		var definition: Resource = entry[4]
+		var enabled: bool = GameState.is_building_unlocked(definition.definition_id)
+		if definition.placement_mode == "planet":
+			enabled = enabled and _planet_under_fleet() != null
+		entry[1].enabled = enabled
+		entry[1].queue_redraw()
 
 
 func _close_build_menu() -> void:
@@ -582,40 +537,17 @@ func _close_build_menu() -> void:
 	build_menu.visible = false
 
 
-func _on_place_ship_lab() -> void:
-	_show_building_info(GameState.BUILDING_SHIP_LAB)
-
-
-func _on_place_transport_hub() -> void:
-	_show_building_info(GameState.BUILDING_TRANSPORT_HUB)
-
-
-func _on_place_extractor() -> void:
-	# The option stays pressable while greyed, so this is also how a
-	# not-over-a-planet extractor explains itself.
-	_show_building_info(GameState.BUILDING_EXTRACTOR)
-
-
 func cost_of(type: String) -> int:
-	match type:
-		GameState.BUILDING_TRANSPORT_HUB:
-			return GameState.TRANSPORT_HUB_COST
-		GameState.BUILDING_SHIP_LAB:
-			return GameState.SHIP_LAB_COST
-		GameState.BUILDING_MOTHERSHIP:
-			return GameState.MOTHERSHIP_COST
-		GameState.BUILDING_SHIP_CRAFTER:
-			return GameState.SHIP_CRAFTER_COST
-		GameState.BUILDING_COMMAND_CENTER:
-			return GameState.COMMAND_CENTER_COST
-		_:
-			return GameState.EXTRACTOR_COST
+	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
+	return int(definition.cost) if definition != null else 0
 
 
 func _show_building_info(type: String) -> void:
-	var info: Dictionary = BUILDING_INFO[type]
-	var cost: int = cost_of(type)
-	var lines: Array = [info.body]
+	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
+	if definition == null:
+		return
+	var cost: int = int(definition.cost)
+	var lines: Array = [definition.description]
 	var can_build: bool = true
 
 	# Locked structures still list themselves, greyed, so the player can see
@@ -626,7 +558,7 @@ func _show_building_info(type: String) -> void:
 
 	# Anything that would stop this particular placement is spelled out in
 	# the same popup, rather than silently failing after the press.
-	if can_build and type == GameState.BUILDING_EXTRACTOR:
+	if can_build and definition.placement_mode == "planet":
 		var planet: Node2D = _planet_under_fleet()
 		if planet == null:
 			lines.append("No planet in reach - fly over one.")
@@ -635,15 +567,15 @@ func _show_building_info(type: String) -> void:
 			lines.append("%s already has an extractor." % planet.planet_name)
 			can_build = false
 		else:
-			lines.append("Will mine %s from %s." % ["gas" if planet.resource_type == "gas" else "ore", planet.planet_name])
-	elif can_build and type == GameState.BUILDING_MOTHERSHIP and GameState.has_mothership():
+			lines.append("Will mine %s from %s." % [GameState.resource_name(planet.resource_type), planet.planet_name])
+	elif can_build and definition.unique and GameState.has_building_of_type(type):
 		lines.append("WARNING: only one may exist - this destroys your current one.")
 
 	if can_build and not GameState.can_afford(cost):
 		lines.append("Not enough rocks - needs %d, you have %d." % [cost, GameState.rocks])
 		can_build = false
 
-	info_title.text = info.title
+	info_title.text = definition.display_name
 	info_message.text = "\n\n".join(lines)
 	info_cost.amount = cost
 	info_build_button.visible = can_build
@@ -668,28 +600,31 @@ func _confirm_build() -> void:
 	# planet an extractor was going to mine.
 	if not GameState.is_building_unlocked(type):
 		return
+	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
+	if definition == null:
+		return
 
-	if type == GameState.BUILDING_EXTRACTOR:
+	if definition.placement_mode == "planet":
 		var planet: Node2D = _planet_under_fleet()
 		if planet == null or GameState.has_extractor_at(planet.planet_name):
 			build_status.text = "No planet in reach any more"
 			return
-		if not GameState.spend(GameState.EXTRACTOR_COST):
-			build_status.text = "Not enough rocks (need %d, have %d)" % [GameState.EXTRACTOR_COST, GameState.rocks]
+		if not GameState.spend(definition.cost):
+			build_status.text = "Not enough rocks (need %d, have %d)" % [definition.cost, GameState.rocks]
 			return
 		GameState.add_extractor(planet.planet_name, planet.position, planet.resource_type)
 		build_menu.visible = false
 		return
 
-	if type == GameState.BUILDING_MOTHERSHIP and GameState.has_mothership():
-		if not GameState.can_afford(GameState.MOTHERSHIP_COST):
+	if definition.unique and GameState.has_building_of_type(type):
+		if not GameState.can_afford(definition.cost):
 			build_status.text = "Not enough rocks (need %d, have %d)" % [
-				GameState.MOTHERSHIP_COST, GameState.rocks
+				definition.cost, GameState.rocks
 			]
 			return
 		# Only now is the old one destroyed - never before the new one is
 		# known to be affordable, or the player would be left with none.
-		GameState.remove_buildings_of_type(GameState.BUILDING_MOTHERSHIP)
+		GameState.remove_buildings_of_type(type)
 		building_field.rebuild_all()
 
 	_try_place(type, cost_of(type))
@@ -768,26 +703,19 @@ func _refresh_craft_status() -> void:
 	# Prices live with the buttons they describe. The top of the screen is
 	# intentionally reserved for the shared resource bar and a short action
 	# message; repeating fleet, queue and transport counts here buried the UI.
-	craft_interceptor_label.text = "Interceptor\n%d ore" % GameState.SHIP_COST
-	craft_transporter_label.text = "Transporter\n%d ore" % GameState.TRANSPORTER_COST
-	craft_shield_label.text = "Shield Vessel\n%d ore" % GameState.SHIELD_COST
 	craft_status.text = ""
-	# Nowhere to station one means the order would be refused, so say so
-	# rather than letting the button look available and do nothing.
-	craft_transporter_button.enabled = GameState.has_transport_hub() \
-		and GameState.can_station_transporter()
-	craft_transporter_button.queue_redraw()
-
-	craft_shield_button.enabled = GameState.shield_vessel_unlocked()
-	craft_shield_button.queue_redraw()
-
-	# Fleet capacity no longer gates ORDERING (#23). A finished vessel waits
-	# at the mothership until the player crews it, so a full fleet is a
-	# reason not to collect one yet - not a reason the crafter cannot build.
-	# This is also what stopped the crafter being inert on a fresh save,
-	# where the fleet starts at exactly its cap.
-	craft_interceptor_button.enabled = true
-	craft_interceptor_button.queue_redraw()
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	for i in range(mini(definitions.size(), craft_vessel_buttons.size())):
+		var definition: Resource = definitions[i]
+		var button: IconButton = craft_vessel_buttons[i]
+		craft_vessel_labels[i].text = "%s\n%d ore" % [definition.display_name, definition.build_cost]
+		button.icon = definition.icon
+		button.glow_color = definition.glow_color
+		button.enabled = GameState.vessel_is_unlocked(definition.definition_id)
+		if definition.has_capability("transport"):
+			button.enabled = button.enabled and GameState.has_transport_hub() \
+				and GameState.can_station_transporter()
+		button.queue_redraw()
 	_refresh_queue()
 	if craft_message != "":
 		if Time.get_ticks_msec() < craft_message_until:
@@ -797,40 +725,40 @@ func _refresh_craft_status() -> void:
 
 
 func _on_craft_interceptor() -> void:
+	_on_craft_vessel(GameState.VESSEL_INTERCEPTOR)
+
+
+func _on_craft_vessel(vessel: String) -> void:
 	if craft_building_id == 0:
 		_say("No crafter selected - reopen this panel from the building")
 		return
-	# No affordability check: an order the crafter cannot pay for yet is
-	# QUEUED, and completes by itself once ore is delivered here (#16). But
-	# queueing silently looks identical to a dead button, so it says which
-	# happened and what the crafter is still short of.
-	GameState.queue_order(craft_building_id)
-	_report_order(GameState.PRODUCT_SHIP)
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(vessel)
+	if definition == null:
+		return
+	if not GameState.queue_order(craft_building_id, vessel):
+		if not GameState.vessel_is_unlocked(vessel):
+			_say("%s must be unlocked at a ship lab first" % definition.display_name)
+		elif definition.has_capability("transport") and not GameState.has_transport_hub():
+			_say("Build a Transport Hub first - a transporter needs somewhere to be stationed")
+		elif definition.has_capability("transport"):
+			_say("All %d berths are taken - build another hub, or research Freight Yards" %
+				GameState.transport_capacity())
+		return
+	_report_order(vessel)
 
 
 func _report_order(product: String) -> void:
 	var short: int = GameState.outstanding_cost(craft_building_id)
 	if short > 0:
 		_say("%s queued - %d more ore must be delivered here" % [
-			GameState.VESSEL_NAMES.get(product, product), short
+			GameState.vessel_name(product), short
 		])
 	else:
-		_say("%s ordered - building now" % GameState.VESSEL_NAMES.get(product, product))
+		_say("%s ordered - building now" % GameState.vessel_name(product))
 
 
 func _on_craft_transporter() -> void:
-	if craft_building_id == 0:
-		_say("No crafter selected - reopen this panel from the building")
-		return
-	if not GameState.queue_order(craft_building_id, GameState.PRODUCT_TRANSPORTER):
-		# Two different refusals, and the player needs to know WHICH.
-		if not GameState.has_transport_hub():
-			_say("Build a Transport Hub first - a transporter needs somewhere to be stationed")
-		else:
-			_say("All %d berths are taken - build another hub, or research Freight Yards" %
-				GameState.transport_capacity())
-		return
-	_refresh_craft_status()
+	_on_craft_vessel(GameState.VESSEL_TRANSPORTER)
 
 
 # --- ship lab (#5) --------------------------------------------------------
@@ -840,10 +768,13 @@ func _lab_options() -> Array:
 	# entry, because unlocking the type and upgrading it belong in the same
 	# place - and its upgrades are pointless until it exists.
 	var options: Array = []
-	if lab_vessel == GameState.VESSEL_SHIELD and not GameState.shield_vessel_unlocked():
-		options.append({"unlock": true, "name": "Unlock Shield Vessel",
-			"desc": "Lets the ship crafter build shield vessels. Its shield absorbs one lethal hit, then cycles back up.",
-			"cost": GameState.UNLOCK_SHIELD_COST})
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(lab_vessel)
+	if definition == null:
+		return options
+	if not GameState.vessel_is_unlocked(lab_vessel):
+		options.append({"unlock": true, "id": definition.unlock_id,
+			"name": definition.unlock_name, "desc": definition.unlock_description,
+			"cost": definition.unlock_cost, "icon": IconButton.Icon.UPGRADE_UNLOCK_SHIELD})
 		return options
 	for u in GameState.upgrades_for(lab_vessel):
 		options.append({"unlock": false, "id": u.id, "name": u.name, "desc": u.desc})
@@ -851,8 +782,10 @@ func _lab_options() -> Array:
 
 
 func _on_lab_vessel(index: int) -> void:
-	lab_vessel = [GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_SHIELD,
-		GameState.VESSEL_TRANSPORTER][index]
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	if index < 0 or index >= definitions.size():
+		return
+	lab_vessel = definitions[index].definition_id
 	lab_choice = 0
 	_refresh_lab()
 
@@ -870,7 +803,7 @@ func _on_lab_buy() -> void:
 	if options.is_empty():
 		return
 	var choice: Dictionary = options[lab_choice]
-	var id: String = GameState.UNLOCK_SHIELD_VESSEL if choice.unlock else String(choice.id)
+	var id: String = String(choice.id)
 	if not GameState.queue_lab_research(lab_building_id, id):
 		lab_status.text = "Research is already queued or complete"
 		return
@@ -879,14 +812,17 @@ func _on_lab_buy() -> void:
 
 
 func _refresh_lab() -> void:
-	for i in range(lab_vessel_buttons.size()):
-		var this_vessel: String = [GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_SHIELD,
-			GameState.VESSEL_TRANSPORTER][i]
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	for i in range(mini(lab_vessel_buttons.size(), definitions.size())):
+		var definition: Resource = definitions[i]
+		var this_vessel: String = definition.definition_id
 		lab_vessel_buttons[i].enabled = true
-		lab_vessel_buttons[i].glow_color = _vessel_colour(this_vessel)
+		lab_vessel_buttons[i].icon = definition.icon
+		lab_vessel_buttons[i].glow_color = definition.glow_color
+		lab_vessel_labels[i].text = definition.display_name
 		lab_vessel_buttons[i].highlighted = this_vessel == lab_vessel
 		lab_vessel_buttons[i].queue_redraw()
-	lab_vessel_label.text = "%s research" % GameState.VESSEL_NAMES.get(lab_vessel, lab_vessel)
+	lab_vessel_label.text = "%s research" % GameState.vessel_name(lab_vessel)
 
 	var options: Array = _lab_options()
 	for i in range(lab_upgrade_buttons.size()):
@@ -896,7 +832,7 @@ func _refresh_lab() -> void:
 		if not visible:
 			continue
 		var option: Dictionary = options[i]
-		var price_text: String = "%d ore" % (GameState.UNLOCK_SHIELD_COST if bool(option.unlock) else GameState.upgrade_cost(option.id))
+		var price_text: String = "%d ore" % (int(option.cost) if bool(option.unlock) else GameState.upgrade_cost(option.id))
 		if not bool(option.unlock) and GameState.upgrade_maxed(option.id):
 			price_text = "MAX"
 		var level_note: String = "" if bool(option.unlock) else "  %d/%d" % [
@@ -924,29 +860,11 @@ func _refresh_lab() -> void:
 
 
 func _upgrade_icon(option: Dictionary) -> IconButton.Icon:
-	if bool(option.unlock):
-		return IconButton.Icon.UPGRADE_UNLOCK_SHIELD
-	match String(option.id):
-		"int_damage": return IconButton.Icon.UPGRADE_DAMAGE
-		"int_rate": return IconButton.Icon.UPGRADE_RATE
-		"int_range": return IconButton.Icon.UPGRADE_RANGE
-		"int_speed", "shd_speed": return IconButton.Icon.UPGRADE_THRUSTERS
-		"shd_hits": return IconButton.Icon.UPGRADE_SHIELD_HITS
-		"shd_recharge": return IconButton.Icon.UPGRADE_SHIELD_RECHARGE
-		"trn_capacity": return IconButton.Icon.UPGRADE_CARGO
-		"trn_speed": return IconButton.Icon.UPGRADE_ENGINES
-		_: return IconButton.Icon.SHIP_LAB
+	return int(option.get("icon", IconButton.Icon.SHIP_LAB))
 
 
 func _on_craft_shield() -> void:
-	if craft_building_id == 0:
-		_say("No crafter selected - reopen this panel from the building")
-		return
-	if not GameState.shield_vessel_unlocked():
-		_say("Shield vessels must be unlocked at a ship lab first")
-		return
-	GameState.queue_order(craft_building_id, GameState.VESSEL_SHIELD)
-	_report_order(GameState.VESSEL_SHIELD)
+	_on_craft_vessel(GameState.VESSEL_SHIELD)
 
 
 # --- moving ore, in both directions, at any building (#24) ----------------
@@ -1033,8 +951,8 @@ func _refresh_queue() -> void:
 		if not slot.visible:
 			continue
 		var order: Dictionary = orders[i]
-		slot.icon = IconButton.Icon.TRANSPORT_HUB if order.product == GameState.PRODUCT_TRANSPORTER \
-			else IconButton.Icon.SHIP
+		var definition: Resource = VESSEL_DEFINITIONS.get_definition(String(order.product))
+		slot.icon = definition.icon
 		slot.glow_color = _vessel_colour(String(order.product))
 		# Only the one under construction reads as active; the rest are
 		# waiting, and greyed says so without needing a caption each.
@@ -1047,29 +965,24 @@ func _refresh_queue() -> void:
 	var head: Dictionary = orders[0]
 	if bool(head.started):
 		queue_detail.text = "Building %s  %d%%\nTap to cancel" % [
-			GameState.VESSEL_NAMES.get(head.product, head.product),
+			GameState.vessel_name(String(head.product)),
 			int(round(float(head.progress) * 100.0)),
 		]
 	else:
 		queue_detail.text = "%s waiting for ore\nTap to cancel" % \
-			GameState.VESSEL_NAMES.get(head.product, head.product)
+			GameState.vessel_name(String(head.product))
 
 
 func _vessel_colour(product: String) -> Color:
-	match product:
-		GameState.VESSEL_SHIELD:
-			return Color(0.45, 0.8, 1.0)
-		GameState.PRODUCT_TRANSPORTER:
-			return Color(0.95, 0.55, 0.85)
-		_:
-			return Color(0.25, 0.85, 1.0)
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(product)
+	return definition.glow_color if definition != null else Color(0.25, 0.85, 1.0)
 
 
 func _on_queue_slot(index: int) -> void:
 	var orders: Array = GameState.order_list(craft_building_id)
 	if index >= orders.size():
 		return
-	var vessel: String = GameState.VESSEL_NAMES.get(orders[index].product, orders[index].product)
+	var vessel: String = GameState.vessel_name(String(orders[index].product))
 	var refunded: bool = bool(orders[index].started)
 	if not GameState.cancel_order(craft_building_id, index):
 		return
@@ -1094,12 +1007,12 @@ func _on_hangar_crew_type(index: int) -> void:
 		return
 	var stored_index: int = GameState.stored_vessels.find(type)
 	if stored_index < 0:
-		hangar_status.text = "No %s available" % GameState.VESSEL_NAMES.get(type, type)
+		hangar_status.text = "No %s available" % GameState.vessel_name(type)
 		return
 	if not fleet.add_ship(GameState.take_stored_vessel(stored_index)):
 		hangar_status.text = "Could not crew that vessel"
 		return
-	hangar_status.text = "%s joined the fleet" % GameState.VESSEL_NAMES.get(type, type)
+	hangar_status.text = "%s joined the fleet" % GameState.vessel_name(type)
 	_refresh_hangar()
 
 
@@ -1111,32 +1024,40 @@ func _on_hangar_store_type(index: int) -> void:
 			ship_index = i
 			break
 	if ship_index < 0:
-		hangar_status.text = "No %s in the fleet" % GameState.VESSEL_NAMES.get(type, type)
+		hangar_status.text = "No %s in the fleet" % GameState.vessel_name(type)
 		return
 	var stored: String = fleet.store_ship(ship_index)
 	if stored == "":
 		hangar_status.text = "Keep one ship deployed"
 		return
 	GameState.stored_vessels.append(stored)
-	hangar_status.text = "%s stored in the hangar" % GameState.VESSEL_NAMES.get(stored, stored)
+	hangar_status.text = "%s stored in the hangar" % GameState.vessel_name(stored)
 	_refresh_hangar()
 
 
 func _hangar_types() -> Array:
-	return [GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_SHIELD, GameState.VESSEL_TRANSPORTER]
+	var types: Array = []
+	for definition in VESSEL_DEFINITIONS.all():
+		types.append(definition.definition_id)
+	return types
 
 
 func _refresh_hangar() -> void:
 	var types: Array = _hangar_types()
 	for i in range(types.size()):
 		var type: String = types[i]
+		var definition: Resource = VESSEL_DEFINITIONS.get_definition(type)
 		var available: int = GameState.stored_vessels.count(type)
 		var deployed: int = 0
 		for ship in fleet.ships:
 			if is_instance_valid(ship) and String(ship.vessel_type) == type:
 				deployed += 1
-		hangar_available_labels[i].text = "%s\n%d available" % [GameState.VESSEL_NAMES.get(type, type), available]
-		hangar_fleet_labels[i].text = "%s\n%d in fleet" % [GameState.VESSEL_NAMES.get(type, type), deployed]
+		hangar_available_labels[i].text = "%s\n%d available" % [definition.display_name, available]
+		hangar_fleet_labels[i].text = "%s\n%d in fleet" % [definition.display_name, deployed]
+		hangar_available_slots[i].icon = definition.icon
+		hangar_fleet_slots[i].icon = definition.icon
+		hangar_available_slots[i].glow_color = definition.glow_color
+		hangar_fleet_slots[i].glow_color = definition.glow_color
 		hangar_available_slots[i].enabled = available > 0 and fleet.ships.size() < GameState.max_fleet_size()
 		hangar_fleet_slots[i].enabled = deployed > 0 and fleet.ships.size() > 1
 		hangar_available_slots[i].queue_redraw()
diff --git a/Building.gd b/Building.gd
index d4387d7..b9dea7e 100644
--- a/Building.gd
+++ b/Building.gd
@@ -1,665 +1,42 @@
 extends Node2D
 
-# A player-placed structure in space. Three kinds for now:
-#   mothership     - where a wiped-out fleet is rebuilt
-#   ship_crafter   - fly the fleet onto it to buy additional ships
-#   command_center - reconfigure the fleet formation
-#
-# Buildings are stationary and harmless; whether the fleet is "on" one is
-# decided by BuildingField comparing the fleet CENTROID against
-# interact_radius, the same stable single-number test Planet uses (see
-# Planet.gd for why per-ship overlap was a poor fit).
-#
-# Nothing here rests on ground or vents into an atmosphere - these are
-# orbital structures, so they are built out of trusses, radiator fins,
-# reactor cores and open cradles rather than walls and roofs.
-#
-# The crafter and the mothership animate, so they run _process. The command
-# centre is drawn once and never redrawn - per-frame redraws of art that
-# never changes were a real framerate cost earlier on.
+const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
 
-@export var building_type: String = "mothership"
-# Which GameState.buildings record this node is showing. Set by
-# BuildingField when it spawns, so a node can be traced back to the stock
-# and production queue that survive the scene swap (#16).
+@export var definition_id: String = "mothership"
 @export var building_id: int = 0
 @export var interact_radius: float = 150.0
 
-const MOTHERSHIP_COLOR: Color = Color(0.45, 0.9, 0.55)
-const CRAFTER_COLOR: Color = Color(1.0, 0.72, 0.25)
-const COMMAND_COLOR: Color = Color(0.55, 0.6, 1.0)
-const TRANSPORT_HUB_COLOR: Color = Color(0.95, 0.55, 0.85)
-const SHIP_LAB_COLOR: Color = Color(0.55, 0.95, 0.9)
+var definition: Resource
+var visual: Node2D
 
-# Ship lab: a test frame with a vessel held in it and instruments sweeping
-# over it. Reads as a workshop rather than a factory - the crafter already
-# owns "assembly line", so this is measurement, not production.
-const LAB_FRAME_W: float = 78.0
-const LAB_FRAME_H: float = 58.0
-const LAB_MOUNT_RADIUS: float = 15.0
-const LAB_SCANNER_ORBIT: float = 96.0
-const LAB_SCAN_SPEED: float = 0.9
-
-# Transport hub: an octagonal dock ring with berths around it and a freight
-# core in the middle. Deliberately radial-but-flat, so it does not read as a
-# small mothership - the mothership is the only thing with swept arms.
-const HUB_RING_RADIUS: float = 74.0
-const HUB_DECK_RADIUS: float = 54.0
-const HUB_CORE_RADIUS: float = 22.0
-const HUB_BERTH_COUNT: int = 8
-const HUB_BERTH_LENGTH: float = 20.0
-const HUB_DOCKED_COUNT: int = 3
-const HUB_DOCKED_ORBIT: float = 96.0
-const HUB_SPIN_SPEED: float = 0.22
-# The vessel on the assembly line is drawn in the fleet's own colour, so it
-# reads as "one of yours being built" rather than as shipyard machinery.
-const HULL_COLOR: Color = Color(0.25, 0.85, 1.0)
-
-# One assembly cycle: parts are welded on, the finished hull flashes, then
-# it clears the cradle and the line starts over.
-const CYCLE: float = 3.6
-const ASSEMBLE_END: float = 0.66   # fraction of CYCLE spent welding
-const FLASH_END: float = 0.76      # ... then the completion flash
-                                   # ... then launch, to 1.0
-
-const CORE_CENTRE: Vector2 = Vector2(-58.0, 12.0)
-const BAY_CENTRE: Vector2 = Vector2(46.0, 12.0)
-const RIB_RADIUS: float = 36.0
-const RAIL_Y: float = -32.0
-const FLASH_RING_RADIUS: float = 20.0
-
-# The hull in four pieces, attached in this order. Each carries the point
-# the crane welds it on at, which is where the sparks fly from.
-const SHIP_PARTS: Array = [
-	{"at": 0.04, "weld": Vector2(0, -12), "points": [Vector2(0, -26), Vector2(-8, 4), Vector2(8, 4)]},
-	{"at": 0.28, "weld": Vector2(-13, 7), "points": [Vector2(-8, -4), Vector2(-22, 14), Vector2(-8, 10)]},
-	{"at": 0.48, "weld": Vector2(13, 7), "points": [Vector2(8, -4), Vector2(22, 14), Vector2(8, 10)]},
-	{"at": 0.70, "weld": Vector2(0, 10), "points": [Vector2(-7, 4), Vector2(7, 4), Vector2(5, 14), Vector2(-5, 14)]},
-]
-
-# The assembly clock, wrapped at CYCLE because the whole build sequence is
-# expressed as a fraction of it.
-var anim_time: float = 0.0
-
-# Free-running seconds for everything that is merely cyclic - reactor pulses,
-# orbiting satellites, blinking beacons. These must NOT share anim_time:
-# CYCLE is 3.6s, which is not a whole number of periods for any of them, so
-# wrapping made every one of them leap at the wrap. The satellites were the
-# obvious casualty, snapping back 66 degrees every 3.6 seconds.
-#
-# Deliberately never wrapped. GDScript floats are 64-bit, so even after hours
-# of play the argument to sin() keeps far more precision than a frame needs,
-# and any wrap point would reintroduce exactly the discontinuity above.
-var phase_time: float = 0.0
-
-var _hull_parts: Array[PackedVector2Array] = []
-
-# Every moving element is its own NeonPiece, rasterised once when the
-# building is created and thereafter only moved, scaled, faded or hidden.
-# Nothing here ever calls queue_redraw() again: the building's own _draw()
-# lays down the fixed structure a single time, and the animation is pure
-# node-property work from then on.
-var _core_cell: NeonPiece = null
-var _satellites: Node2D = null
-var _beacons: Array = []
-var _clamps: NeonPiece = null
-var _crane: Node2D = null
-var _hoist: NeonPiece = null
-var _sparks: Node2D = null
-var _hull_holder: Node2D = null
-var _hull_pieces: Array = []
-# Rotating holder for the transports stationed at a transport hub (#18).
-var _hub_traffic: Node2D = null
-# Sweeping instrument booms at a ship lab (#5).
-var _lab_scanners: Node2D = null
-var _flash_ring: NeonPiece = null
-var _wash: NeonPiece = null
+var building_type: String:
+	get: return definition_id
+	set(value): definition_id = value
 
 
 func _ready() -> void:
 	add_to_group("buildings")
 	z_index = -1
-	# The crafter runs an assembly line and the mothership holds a live
-	# reactor with satellites in orbit, so both animate. The command centre is
-	# entirely static and needs no per-frame work at all.
-	var animated: bool = building_type != GameState.BUILDING_COMMAND_CENTER
-	set_process(animated)
-	if building_type == GameState.BUILDING_SHIP_CRAFTER:
-		for part in SHIP_PARTS:
-			_hull_parts.append(PackedVector2Array(part.points))
-		_build_crafter_pieces()
-	elif building_type == GameState.BUILDING_MOTHERSHIP:
-		_build_mothership_pieces()
-	elif building_type == GameState.BUILDING_TRANSPORT_HUB:
-		_build_hub_pieces()
-	elif building_type == GameState.BUILDING_SHIP_LAB:
-		_build_lab_pieces()
-	queue_redraw()
+	definition = BUILDING_DEFINITIONS.get_definition(definition_id)
+	if definition == null or definition.visual_scene == null:
+		return
+	visual = definition.visual_scene.instantiate()
+	get_node("VisualHost").add_child(visual)
 
 
-func _process(delta: float) -> void:
-	anim_time = fmod(anim_time + delta, CYCLE)
-	phase_time += delta
-	apply_animation()
+func available_actions() -> PackedStringArray:
+	if visual == null:
+		return PackedStringArray()
+	var provider: Node = visual.get_node_or_null("ActionProvider")
+	return provider.actions if provider != null else PackedStringArray()
 
 
-# Pushes the current clock onto the movable pieces. Normally driven from
-# _process; public so a preview or a test can pin the clock and see exactly
-# that frame without having to run the animation up to it in real time.
-func apply_animation() -> void:
-	match building_type:
-		GameState.BUILDING_MOTHERSHIP:
-			_animate_mothership()
-		GameState.BUILDING_SHIP_CRAFTER:
-			_animate_crafter()
-		GameState.BUILDING_TRANSPORT_HUB:
-			_animate_transport_hub()
-		GameState.BUILDING_SHIP_LAB:
-			_animate_ship_lab()
-
-
-# Where the satellites are, and how open the reactor core is. Both are read
-# by _draw and by the test that checks they stay continuous across the
-# assembly clock's wrap.
-func orbit_angle() -> float:
-	return phase_time * ORBIT_SPEED
-
-
-func core_pulse() -> float:
-	return 0.5 + 0.5 * sin(phase_time * PULSE_SPEED)
+func primary_action() -> String:
+	for action in available_actions():
+		if action != "transfer" and action != "hangar":
+			return action
+	return ""
 
 
 func get_display_name() -> String:
-	match building_type:
-		GameState.BUILDING_MOTHERSHIP:
-			return "Mothership"
-		GameState.BUILDING_SHIP_CRAFTER:
-			return "Ship Crafter"
-		_:
-			return "Command Center"
-
-
-# How many times this building's geometry has actually been rasterised. The
-# whole point of the NeonPiece decomposition is that this stays at 1 for the
-# building's lifetime however long it animates, so it is worth being able to
-# assert rather than assume.
-var draw_count: int = 0
-
-
-func _draw() -> void:
-	draw_count += 1
-	# Runs exactly once per building: this is the fixed structure. Everything
-	# that moves is a NeonPiece child, animated through node properties, so
-	# nothing here ever asks for a redraw again.
-	match building_type:
-		GameState.BUILDING_COMMAND_CENTER:
-			_draw_command_center()
-		GameState.BUILDING_MOTHERSHIP:
-			_draw_mothership_static(self)
-		GameState.BUILDING_TRANSPORT_HUB:
-			_draw_transport_hub_static(self)
-		GameState.BUILDING_SHIP_LAB:
-			_draw_ship_lab_static(self)
-		_:
-			_draw_crafter_static(self)
-
-
-# --- shared helpers -------------------------------------------------------
-
-func _ring(centre: Vector2, radius: float, sides: int, phase: float = 0.0) -> PackedVector2Array:
-	var pts: PackedVector2Array = PackedVector2Array()
-	for i in range(sides):
-		var a: float = (float(i) / float(sides)) * TAU + phase
-		pts.append(centre + Vector2(cos(a), sin(a)) * radius)
-	return pts
-
-
-func _arc(centre: Vector2, radius: float, from_a: float, to_a: float, steps: int) -> PackedVector2Array:
-	var pts: PackedVector2Array = PackedVector2Array()
-	for i in range(steps + 1):
-		var a: float = lerpf(from_a, to_a, float(i) / float(steps))
-		pts.append(centre + Vector2(cos(a), sin(a)) * radius)
-	return pts
-
-
-
-
-# --- command centre: a tactical plotting hub ------------------------------
-# The mothership is radial-and-swept, the crafter is an asymmetric assembly
-# line, so the command centre reads best as the odd one out: rigid, hexagonal,
-# a wheel rather than a claw. Six spokes tie a hex rim to a central diamond
-# readout, and every spoke ends in a formation port - half of them holding a
-# token, half left open - so the structure itself shows fleet slots waiting
-# to be filled, which is exactly what the drag-and-drop editor inside does.
-
-const CMD_HEX_RADIUS: float = 88.0
-const CMD_DECK_RADIUS: float = 66.0
-const CMD_HUB_RADIUS: float = 30.0
-const CMD_SCREEN_RADIUS: float = 14.0
-const CMD_PORT_COUNT: int = 6
-const CMD_PORT_LENGTH: float = 16.0
-const CMD_TOKEN_RADIUS: float = 9.0
-const CMD_STUD_RADIUS: float = 7.0
-
-
-# --- ship lab -------------------------------------------------------------
-
-func _draw_ship_lab_static(target: CanvasItem) -> void:
-	var c: Color = SHIP_LAB_COLOR
-
-	# Outer test frame, open at the corners so it reads as a rig rather than
-	# a solid hull.
-	for sx in [-1.0, 1.0]:
-		for sy in [-1.0, 1.0]:
-			var corner: Vector2 = Vector2(sx * LAB_FRAME_W, sy * LAB_FRAME_H)
-			NeonDraw.draw_glowing_line(target, corner,
-				corner - Vector2(sx * LAB_FRAME_W * 0.45, 0.0), c, 0.9, 0.42)
-			NeonDraw.draw_glowing_line(target, corner,
-				corner - Vector2(0.0, sy * LAB_FRAME_H * 0.5), c, 0.9, 0.42)
-
-	# The vessel under test, held nose-up in the middle - deliberately the
-	# fleet's own silhouette, so it is obvious what the lab is for.
-	NeonDraw.draw_glowing_polygon(target, PackedVector2Array([
-		Vector2(0, -26), Vector2(13, 12), Vector2(0, 5), Vector2(-13, 12),
-	]), HULL_COLOR, 0.95)
-
-	# Mount ring and its bracing.
-	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, LAB_MOUNT_RADIUS, 6, PI / 6.0), c, 0.5,
-		NeonDraw.DEFAULT_CORE, 0.7)
-	for i in range(4):
-		var a: float = (float(i) / 4.0) * TAU + PI / 4.0
-		var dir: Vector2 = Vector2(cos(a), sin(a))
-		NeonDraw.draw_glowing_line(target, dir * LAB_MOUNT_RADIUS, dir * 40.0, c, 0.45, 0.3)
-
-
-func _build_lab_pieces() -> void:
-	# Two instrument booms sweeping round the vessel. One holder, rasterised
-	# once, rotated per frame (#10).
-	_lab_scanners = Node2D.new()
-	add_child(_lab_scanners)
-	for i in range(2):
-		var a: float = float(i) * PI
-		var at: Vector2 = Vector2(cos(a), sin(a)) * LAB_SCANNER_ORBIT
-		var piece: NeonPiece = NeonPiece.create(_lab_scanners, at, SHIP_LAB_COLOR)
-		piece.add_polygon(PackedVector2Array([
-			Vector2(-4, -12), Vector2(4, -12), Vector2(4, 12), Vector2(-4, 12),
-		]))
-		piece.add_line(Vector2(0, 0), Vector2(-cos(a), -sin(a)) * 26.0, 0.3, 0.5)
-		piece.rotation = a
-		piece.queue_redraw()
-
-
-func _animate_ship_lab() -> void:
-	_lab_scanners.rotation = phase_time * LAB_SCAN_SPEED
-
-
-# --- transport hub --------------------------------------------------------
-
-func _draw_transport_hub_static(target: CanvasItem) -> void:
-	var c: Color = TRANSPORT_HUB_COLOR
-
-	# Dock ring and the deck nested inside it.
-	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, HUB_RING_RADIUS, HUB_BERTH_COUNT, PI / 8.0), c, 1.0)
-	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, HUB_DECK_RADIUS, HUB_BERTH_COUNT, PI / 8.0), c, 0.45, NeonDraw.DEFAULT_CORE, 0.7)
-
-	# Freight core: a squared-off hold rather than a reactor, so it reads as
-	# storage and not as another power plant.
-	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, HUB_CORE_RADIUS, 4, PI / 4.0), c, 0.95)
-
-	for i in range(HUB_BERTH_COUNT):
-		var a: float = (float(i) / HUB_BERTH_COUNT) * TAU + PI / 8.0
-		var dir: Vector2 = Vector2(cos(a), sin(a))
-		NeonDraw.draw_glowing_line(target, dir * HUB_CORE_RADIUS, dir * HUB_DECK_RADIUS, c, 0.5, 0.32)
-		# Berth arm standing off the ring, where a transporter parks.
-		NeonDraw.draw_glowing_line(target, dir * HUB_RING_RADIUS,
-			dir * (HUB_RING_RADIUS + HUB_BERTH_LENGTH), c, 0.75, 0.38)
-
-
-func _build_hub_pieces() -> void:
-	# Stationed transports, as NeonPiece children of one holder that turns.
-	# Per #10 the geometry is rasterised once and only the holder's rotation
-	# changes, so the traffic costs no redraws at all.
-	_hub_traffic = Node2D.new()
-	add_child(_hub_traffic)
-	for i in range(HUB_DOCKED_COUNT):
-		var a: float = (float(i) / HUB_DOCKED_COUNT) * TAU
-		var at: Vector2 = Vector2(cos(a), sin(a)) * HUB_DOCKED_ORBIT
-		var piece: NeonPiece = NeonPiece.create(_hub_traffic, at, TRANSPORT_HUB_COLOR)
-		# A stubby freighter: blunt, boxy, nothing like the fleet's darts.
-		piece.add_polygon(PackedVector2Array([
-			Vector2(-9, -5), Vector2(9, -5), Vector2(12, 0), Vector2(9, 5), Vector2(-9, 5),
-		]))
-		piece.rotation = a + PI / 2.0
-		piece.queue_redraw()
-
-
-func _animate_transport_hub() -> void:
-	_hub_traffic.rotation = phase_time * HUB_SPIN_SPEED
-
-
-func _diamond(centre: Vector2, r: float) -> PackedVector2Array:
-	return PackedVector2Array([
-		centre + Vector2(0, -r), centre + Vector2(r, 0),
-		centre + Vector2(0, r), centre + Vector2(-r, 0),
-	])
-
-
-func _draw_command_center() -> void:
-	var c: Color = COMMAND_COLOR
-	var readout: Color = Color(0.82, 0.86, 1.0)
-
-	# The rim: a hex table holding the whole layout together, with a fainter
-	# deck ring nested just inside it - the same "plating has layers" read the
-	# mothership gets from its nested reactor rings.
-	NeonDraw.draw_glowing_polygon(self, _ring(Vector2.ZERO, CMD_HEX_RADIUS, CMD_PORT_COUNT, PI / 6.0), c, 1.0)
-	NeonDraw.draw_glowing_polygon(self, _ring(Vector2.ZERO, CMD_DECK_RADIUS, CMD_PORT_COUNT, PI / 6.0), c, 0.5, NeonDraw.DEFAULT_CORE, 0.7)
-
-	for i in range(CMD_PORT_COUNT):
-		var a: float = (float(i) / CMD_PORT_COUNT) * TAU + PI / 6.0
-		var dir: Vector2 = Vector2(cos(a), sin(a))
-		# Spoke bracing the hub to the rim.
-		NeonDraw.draw_glowing_line(self, dir * CMD_HUB_RADIUS, dir * CMD_HEX_RADIUS, c, 0.65, 0.36)
-		# Socket where the mast plugs into the rim.
-		NeonDraw.draw_glowing_polygon(self, _ring(dir * CMD_HEX_RADIUS, CMD_STUD_RADIUS, 6, a), c, 0.85)
-		# Port mast standing proud of the rim; every other one is manned.
-		var port_tip: Vector2 = dir * (CMD_HEX_RADIUS + CMD_PORT_LENGTH)
-		NeonDraw.draw_glowing_line(self, dir * CMD_HEX_RADIUS, port_tip, c, 0.8, 0.4)
-		if i % 2 == 0:
-			NeonDraw.draw_glowing_polygon(self, _diamond(port_tip, CMD_TOKEN_RADIUS), c, 1.0)
-
-	# Command core: a diamond hub with a lit readout set inside it.
-	NeonDraw.draw_glowing_polygon(self, _diamond(Vector2.ZERO, CMD_HUB_RADIUS), c, 1.0)
-	NeonDraw.draw_glowing_polygon(self, _diamond(Vector2.ZERO, CMD_SCREEN_RADIUS), readout, 0.9)
-
-
-# --- mothership: a radial flagship ----------------------------------------
-# Not a big fighter. A mothership is the thing everything else orbits, so it
-# is built radially around a reactor core rather than pointed in a direction:
-# six swept talons, crystal panels set between them, and satellites circling
-# the whole assembly. A forward-facing hull, however large, just reads as
-# another ship.
-
-const ARM_COUNT: int = 6
-const ARM_INNER: float = 42.0
-const ARM_OUTER: float = 106.0
-const ARM_SWEEP: float = 0.72
-const SATELLITE_COUNT: int = 4
-const SATELLITE_ORBIT: float = 126.0
-const ORBIT_SPEED: float = 0.32
-const PULSE_SPEED: float = 2.4
-
-
-func _talon(base_angle: float) -> PackedVector2Array:
-	# One swept claw: the outer edge runs from the core to the tip, and the
-	# inner edge comes back a little behind it, closing to a point so the arm
-	# tapers instead of ending in a blunt stub.
-	var steps: int = 7
-	var pts: PackedVector2Array = PackedVector2Array()
-	for i in range(steps + 1):
-		var f: float = float(i) / float(steps)
-		var a: float = base_angle + ARM_SWEEP * pow(f, 1.3)
-		pts.append(Vector2(cos(a), sin(a)) * lerpf(ARM_INNER, ARM_OUTER, f))
-	for i in range(steps, -1, -1):
-		var f: float = float(i) / float(steps)
-		var trail: float = 0.34 * (1.0 - f) + 0.04
-		var a: float = base_angle + ARM_SWEEP * pow(f, 1.3) - trail
-		pts.append(Vector2(cos(a), sin(a)) * lerpf(ARM_INNER, ARM_OUTER, f))
-	return pts
-
-
-func _draw_mothership_static(canvas: CanvasItem) -> void:
-	var c: Color = MOTHERSHIP_COLOR
-	for i in range(ARM_COUNT):
-		var base: float = (float(i) / float(ARM_COUNT)) * TAU
-		NeonDraw.draw_glowing_polygon(canvas, _talon(base), c, 0.95)
-		# Crystal panel set into the gap behind each arm.
-		var pa: float = base - 0.30
-		NeonDraw.draw_glowing_polygon(canvas, PackedVector2Array([
-			Vector2(cos(pa - 0.11), sin(pa - 0.11)) * 54.0,
-			Vector2(cos(pa + 0.11), sin(pa + 0.11)) * 54.0,
-			Vector2(cos(pa + 0.15), sin(pa + 0.15)) * 86.0,
-			Vector2(cos(pa - 0.15), sin(pa - 0.15)) * 86.0,
-		]), c, 0.7)
-
-	# Reactor housing: the nested rings around the cell that breathes.
-	NeonDraw.draw_glowing_polygon(canvas, _ring(Vector2.ZERO, 38.0, 6, PI / 6.0), c, 1.0)
-	NeonDraw.draw_glowing_polygon(canvas, _ring(Vector2.ZERO, 24.0, 6, 0.0), c, 0.85)
-
-
-const CORE_CELL_RADIUS: float = 12.0
-
-
-func _build_mothership_pieces() -> void:
-	var core_color: Color = Color(0.75, 1.0, 0.85)
-
-	# The breathing cell: drawn at a reference size and then scaled, rather
-	# than rebuilt at a new radius every frame.
-	_core_cell = NeonPiece.create(self, Vector2.ZERO, core_color)
-	_core_cell.add_polygon(_ring(Vector2.ZERO, CORE_CELL_RADIUS, 6, PI / 6.0))
-
-	# Satellites sit at fixed offsets inside a holder; the orbit is the
-	# holder's rotation, so four hexagon pairs become one transform update.
-	_satellites = Node2D.new()
-	add_child(_satellites)
-	for i in range(SATELLITE_COUNT):
-		var a: float = (float(i) / float(SATELLITE_COUNT)) * TAU
-		var at: Vector2 = Vector2(cos(a), sin(a)) * SATELLITE_ORBIT
-		var shell: NeonPiece = NeonPiece.create(_satellites, at, MOTHERSHIP_COLOR)
-		shell.add_polygon(_ring(Vector2.ZERO, 10.0, 6, PI / 6.0), 0.85)
-		var cell: NeonPiece = NeonPiece.create(_satellites, at, core_color)
-		cell.add_polygon(_ring(Vector2.ZERO, 4.5, 6, PI / 6.0), 0.8)
-
-
-func _animate_mothership() -> void:
-	var breath: float = core_pulse()
-	var radius: float = lerpf(9.0, 15.0, breath)
-	_core_cell.scale = Vector2.ONE * (radius / CORE_CELL_RADIUS)
-	_core_cell.modulate.a = lerpf(0.55, 1.0, breath)
-	_satellites.rotation = orbit_angle()
-
-
-# --- ship crafter: an orbital yard with a hull in the cradle --------------
-
-func _draw_crafter_static(canvas: CanvasItem) -> void:
-	var c: Color = CRAFTER_COLOR
-
-	# Fabricator core housing. This replaces the chimney - nothing vents
-	# smoke in vacuum.
-	NeonDraw.draw_glowing_polygon(canvas, _ring(CORE_CENTRE, 26.0, 6, PI / 6.0), c, 1.0)
-
-	# Radiator fins above and below the core, slatted like real ones.
-	for dir_y in [-1.0, 1.0]:
-		var fin: PackedVector2Array = PackedVector2Array([
-			CORE_CENTRE + Vector2(-16, 30 * dir_y), CORE_CENTRE + Vector2(18, 34 * dir_y),
-			CORE_CENTRE + Vector2(24, 54 * dir_y), CORE_CENTRE + Vector2(-10, 50 * dir_y),
-		])
-		NeonDraw.draw_glowing_polygon(canvas, fin, c, 0.75)
-		for f in [0.35, 0.68]:
-			NeonDraw.draw_glowing_line(canvas,
-				fin[0].lerp(fin[3], f), fin[1].lerp(fin[2], f), c, 0.5, 0.28)
-
-	# Truss spine linking the core to the cradle: two rails with X-bracing,
-	# the standard "this was assembled in orbit" read.
-	var spine_top: float = 4.0
-	var spine_bottom: float = 22.0
-	NeonDraw.draw_glowing_line(canvas, Vector2(-32, spine_top), Vector2(14, spine_top), c, 0.9, 0.4)
-	NeonDraw.draw_glowing_line(canvas, Vector2(-32, spine_bottom), Vector2(14, spine_bottom), c, 0.9, 0.4)
-	for i in range(3):
-		var x0: float = -32.0 + float(i) * 15.0
-		var x1: float = x0 + 15.0
-		NeonDraw.draw_glowing_line(canvas, Vector2(x0, spine_top), Vector2(x1, spine_bottom), c, 0.55, 0.28)
-		NeonDraw.draw_glowing_line(canvas, Vector2(x0, spine_bottom), Vector2(x1, spine_top), c, 0.55, 0.28)
-
-	# Construction cradle: two open ribs holding the hull, with the crane
-	# rail overhead. Open at the top so the finished hull can clear it.
-	NeonDraw.draw_glowing_path(canvas, _arc(BAY_CENTRE, RIB_RADIUS, 2.10, 4.18, 7), c, 1.0, 0.7)
-	NeonDraw.draw_glowing_path(canvas, _arc(BAY_CENTRE, RIB_RADIUS, -1.04, 1.04, 7), c, 1.0, 0.7)
-	NeonDraw.draw_glowing_line(canvas, Vector2(10, RAIL_Y), Vector2(82, RAIL_Y), c, 0.9, 0.55)
-	for side in [-1.0, 1.0]:
-		NeonDraw.draw_glowing_line(canvas,
-			BAY_CENTRE + Vector2(RIB_RADIUS * side, -6.0), Vector2(BAY_CENTRE.x + 44.0 * side, RAIL_Y), c, 0.7, 0.3)
-
-
-
-func _build_crafter_pieces() -> void:
-	var c: Color = CRAFTER_COLOR
-
-	# The core's inner cell: fades with the reactor rather than being redrawn
-	# at a new brightness each frame.
-	_core_cell = NeonPiece.create(self, CORE_CENTRE, Color(1.0, 0.9, 0.6))
-	_core_cell.add_polygon(_ring(Vector2.ZERO, 12.0, 6, PI / 6.0))
-
-	# Docking beacons, blinking out of step with each other.
-	for i in range(2):
-		var lamp: Vector2 = BAY_CENTRE + Vector2(-RIB_RADIUS + 2.0 + float(i) * (RIB_RADIUS * 2.0 - 4.0), 30.0)
-		var beacon: NeonPiece = NeonPiece.create(self, lamp, Color(1.0, 0.95, 0.75))
-		beacon.add_polygon(_ring(Vector2.ZERO, 3.0, 4))
-		_beacons.append(beacon)
-
-	# Clamp arms reaching in from each rib. They let go as the hull launches,
-	# which is a fade rather than a redraw.
-	_clamps = NeonPiece.create(self, Vector2.ZERO, c)
-	for side in [-1.0, 1.0]:
-		var outer: Vector2 = BAY_CENTRE + Vector2(RIB_RADIUS * side, 6.0)
-		var inner: Vector2 = BAY_CENTRE + Vector2(24.0 * side, 6.0)
-		_clamps.add_line(outer, inner, 0.35)
-		_clamps.add_line(inner + Vector2(0, -5), inner + Vector2(0, 5), 0.3)
-
-	# Crane: the head rides the rail, so only its x moves. The hoist is drawn
-	# one unit long and stretched with scale.y to reach whatever seam is
-	# being welded - stretching a line needs no redraw, redrawing it would.
-	_crane = Node2D.new()
-	add_child(_crane)
-	var head: NeonPiece = NeonPiece.create(_crane, Vector2.ZERO, c)
-	head.add_polygon(PackedVector2Array([
-		Vector2(-10, -7), Vector2(10, -7), Vector2(6, 6), Vector2(-6, 6),
-	]))
-	head.add_line(Vector2(0, -7), Vector2(0, RAIL_Y - (RAIL_Y + 13.0)), 0.35, 0.8)
-	_hoist = NeonPiece.create(_crane, Vector2(0, 6), c, 0.5)
-	_hoist.add_line(Vector2.ZERO, Vector2(0, 1), 0.3)
-
-	# Weld sparks: four spokes on a holder that spins and stretches. The
-	# jitter is genuinely procedural, but rotating and scaling a holder gives
-	# the same flicker without re-tessellating the spokes every frame.
-	_sparks = Node2D.new()
-	add_child(_sparks)
-	for i in range(4):
-		var a: float = float(i) * TAU / 4.0
-		var spark: NeonPiece = NeonPiece.create(_sparks, Vector2.ZERO, Color(1.0, 0.95, 0.7))
-		spark.add_line(Vector2.ZERO, Vector2(cos(a), sin(a)) * 11.0, 0.3)
-
-	# The hull under construction. Each part is its own piece so attaching one
-	# is a `visible` flip, and the launch is the holder's position and alpha.
-	_hull_holder = Node2D.new()
-	add_child(_hull_holder)
-	for i in range(_hull_parts.size()):
-		var part: NeonPiece = NeonPiece.create(_hull_holder, Vector2.ZERO, HULL_COLOR)
-		part.add_polygon(_hull_parts[i])
-		part.visible = false
-		_hull_pieces.append(part)
-
-	# Engine wash under the hull, and the completion ring. The ring is drawn
-	# at a reference radius and scaled outwards.
-	_wash = NeonPiece.create(_hull_holder, Vector2.ZERO, Color(1.0, 0.85, 0.45), 0.0)
-	for dx in [-4.0, 4.0]:
-		_wash.add_line(Vector2(dx, 14), Vector2(dx * 1.6, 30.0), 0.45)
-
-	_flash_ring = NeonPiece.create(self, BAY_CENTRE, HULL_COLOR, 0.0)
-	_flash_ring.add_polygon(_ring(Vector2.ZERO, FLASH_RING_RADIUS, 6, PI / 6.0))
-
-
-func _animate_crafter() -> void:
-	var t: float = anim_time / CYCLE
-
-	_core_cell.modulate.a = 0.45 + 0.55 * (0.5 + 0.5 * sin(phase_time * 4.0))
-	for i in range(_beacons.size()):
-		_beacons[i].modulate.a = 0.15 + 0.45 * (0.5 + 0.5 * sin(phase_time * 6.0 + float(i) * PI))
-
-	if t < ASSEMBLE_END:
-		_animate_assembly(t / ASSEMBLE_END)
-	elif t < FLASH_END:
-		_animate_completion_flash((t - ASSEMBLE_END) / (FLASH_END - ASSEMBLE_END))
-	else:
-		_animate_launch((t - FLASH_END) / (1.0 - FLASH_END))
-
-
-# How many pieces are on the hull at this point through the assembly phase.
-# Parts attach in order, so this is just how many thresholds have passed.
-func attached_part_count(p: float) -> int:
-	var n: int = 0
-	for part in SHIP_PARTS:
-		if p >= float(part.at):
-			n += 1
-	return n
-
-
-func _place_hull(centre: Vector2, alpha: float) -> void:
-	# The parts are defined around their own origin, so the holder goes
-	# straight to the point they should be centred on.
-	_hull_holder.position = centre
-	_hull_holder.modulate.a = alpha
-
-
-func _animate_assembly(p: float) -> void:
-	_clamps.visible = true
-	_clamps.modulate.a = 0.8
-	_flash_ring.modulate.a = 0.0
-	_wash.modulate.a = 0.0
-	_place_hull(BAY_CENTRE, 1.0)
-
-	var next_part: int = attached_part_count(p)
-	for i in range(_hull_pieces.size()):
-		var attached: bool = i < next_part
-		_hull_pieces[i].visible = attached
-		if attached:
-			# Freshly attached parts flare, then settle to full brightness.
-			var age: float = p - float(SHIP_PARTS[i].at)
-			_hull_pieces[i].modulate.a = 1.0 if age > 0.08 else lerpf(0.3, 1.0, age / 0.08)
-
-	# The crane rides the rail over whichever seam is being worked, and
-	# retracts once there is nothing left to attach.
-	var weld: Vector2 = BAY_CENTRE + (SHIP_PARTS[mini(next_part, SHIP_PARTS.size() - 1)].weld as Vector2)
-	if next_part >= _hull_pieces.size():
-		weld.y = RAIL_Y + 16.0
-	_crane.position = Vector2(weld.x, RAIL_Y + 13.0)
-	_hoist.scale.y = maxf(weld.y - (RAIL_Y + 19.0), 1.0)
-
-	var welding: bool = next_part < _hull_pieces.size()
-	_sparks.visible = welding
-	if welding:
-		var flicker: float = 0.45 + 0.55 * absf(sin(phase_time * 34.0))
-		_sparks.position = weld
-		_sparks.rotation = phase_time * 7.0
-		_sparks.scale = Vector2.ONE * (0.55 + 0.45 * flicker)
-		_sparks.modulate.a = flicker
-
-
-func _animate_completion_flash(p: float) -> void:
-	# Whole hull, clamps springing open, and a ring pushing outwards to mark
-	# it as finished.
-	_clamps.modulate.a = 1.0 - p
-	_sparks.visible = false
-	_place_hull(BAY_CENTRE, 1.0)
-	for piece in _hull_pieces:
-		piece.visible = true
-		piece.modulate.a = 1.0
-	# Retracted, so it does not hang over the finished hull.
-	_crane.position = Vector2(BAY_CENTRE.x, RAIL_Y + 13.0)
-	_hoist.scale.y = 1.0
-	_flash_ring.modulate.a = 1.0 - p
-	_flash_ring.scale = Vector2.ONE * (lerpf(18.0, 56.0, p) / FLASH_RING_RADIUS)
-
-
-func _animate_launch(p: float) -> void:
-	# Clears the cradle and fades out; the next cycle starts from bare ribs.
-	_clamps.modulate.a = 0.0
-	_sparks.visible = false
-	_flash_ring.modulate.a = 0.0
-	var eased: float = p * p
-	var fade: float = clampf(1.0 - p * 1.15, 0.0, 1.0)
-	_place_hull(BAY_CENTRE + Vector2(0.0, -124.0 * eased), fade)
-	for piece in _hull_pieces:
-		piece.visible = true
-		piece.modulate.a = 1.0
-	# Engine wash, strongest just after it breaks free of the clamps.
-	_wash.modulate.a = 0.4 + 0.6 * sin(minf(p * 3.2, PI))
+	return String(definition.display_name) if definition != null else definition_id.capitalize()
diff --git a/Building.tscn b/Building.tscn
index 174c302..3929101 100644
--- a/Building.tscn
+++ b/Building.tscn
@@ -4,3 +4,5 @@
 
 [node name="Building" type="Node2D"]
 script = ExtResource("1")
+
+[node name="VisualHost" type="Node2D" parent="."]
diff --git a/BuildingActionProvider.gd b/BuildingActionProvider.gd
new file mode 100644
index 0000000..1a9dba8
--- /dev/null
+++ b/BuildingActionProvider.gd
@@ -0,0 +1,3 @@
+extends Node
+
+@export var actions: PackedStringArray = []
diff --git a/BuildingActionProvider.gd.uid b/BuildingActionProvider.gd.uid
new file mode 100644
index 0000000..e5e07f8
--- /dev/null
+++ b/BuildingActionProvider.gd.uid
@@ -0,0 +1 @@
+uid://c4dah6xluvenl
diff --git a/BuildingDefinition.gd b/BuildingDefinition.gd
new file mode 100644
index 0000000..fdc990e
--- /dev/null
+++ b/BuildingDefinition.gd
@@ -0,0 +1,20 @@
+class_name BuildingDefinition
+extends Resource
+
+@export var definition_id: String
+@export var display_name: String
+@export_multiline var description: String
+@export var cost: int
+@export var action_icon: int
+@export var menu_icon: int
+@export var visual_scene: PackedScene
+@export var capabilities: PackedStringArray = []
+@export var map_color: Color = Color.WHITE
+@export var map_sides: int = 4
+@export var map_radius: float = 7.0
+@export var map_phase: float = 0.0
+@export var menu_button_name: String
+@export var menu_label_name: String
+@export var menu_cost_name: String
+@export_enum("space", "planet") var placement_mode: String = "space"
+@export var unique: bool = false
diff --git a/BuildingDefinition.gd.uid b/BuildingDefinition.gd.uid
new file mode 100644
index 0000000..7473bd0
--- /dev/null
+++ b/BuildingDefinition.gd.uid
@@ -0,0 +1 @@
+uid://d10s0frtxiw62
diff --git a/BuildingDefinitions.gd b/BuildingDefinitions.gd
new file mode 100644
index 0000000..f05bf8e
--- /dev/null
+++ b/BuildingDefinitions.gd
@@ -0,0 +1,21 @@
+class_name BuildingDefinitions
+extends RefCounted
+
+const ORDER: PackedStringArray = ["mothership", "ship_crafter", "command_center", "extractor", "transport_hub", "ship_lab"]
+const DEFINITIONS: Dictionary = {
+	"mothership": preload("res://MothershipBuildingDefinition.tres"),
+	"ship_crafter": preload("res://CrafterBuildingDefinition.tres"),
+	"command_center": preload("res://CommandBuildingDefinition.tres"),
+	"extractor": preload("res://ExtractorBuildingDefinition.tres"),
+	"transport_hub": preload("res://TransportHubBuildingDefinition.tres"),
+	"ship_lab": preload("res://ShipLabBuildingDefinition.tres"),
+}
+
+static func get_definition(definition_id: String) -> Resource:
+	return DEFINITIONS.get(definition_id)
+
+static func all() -> Array:
+	var result: Array = []
+	for definition_id in ORDER:
+		result.append(DEFINITIONS[definition_id])
+	return result
diff --git a/BuildingDefinitions.gd.uid b/BuildingDefinitions.gd.uid
new file mode 100644
index 0000000..0dead32
--- /dev/null
+++ b/BuildingDefinitions.gd.uid
@@ -0,0 +1 @@
+uid://cpm0u3gu0exke
diff --git a/BuildingField.gd b/BuildingField.gd
index 496c26a..09b37bd 100644
--- a/BuildingField.gd
+++ b/BuildingField.gd
@@ -50,7 +50,7 @@ func get_building_fleet_is_on() -> Node2D:
 func _spawn(record: Dictionary) -> void:
 	var b: Node2D = building_scene.instantiate()
 	b.position = record.position
-	b.building_type = record.type
+	b.definition_id = record.type
 	b.building_id = int(record.get("id", 0))
 	# Deferred for the same reason as the other field spawners: this can run
 	# from inside a parent's _ready() chain, where a direct add_child() is
diff --git a/BuildingVisualBase.gd b/BuildingVisualBase.gd
new file mode 100644
index 0000000..cd339b3
--- /dev/null
+++ b/BuildingVisualBase.gd
@@ -0,0 +1,606 @@
+class_name BuildingVisualBase
+extends Node2D
+
+# A player-placed structure in space. Three kinds for now:
+#   mothership     - where a wiped-out fleet is rebuilt
+#   ship_crafter   - fly the fleet onto it to buy additional ships
+#   command_center - reconfigure the fleet formation
+#
+# Buildings are stationary and harmless; whether the fleet is "on" one is
+# decided by BuildingField comparing the fleet CENTROID against
+# interact_radius, the same stable single-number test Planet uses (see
+# Planet.gd for why per-ship overlap was a poor fit).
+#
+# Nothing here rests on ground or vents into an atmosphere - these are
+# orbital structures, so they are built out of trusses, radiator fins,
+# reactor cores and open cradles rather than walls and roofs.
+#
+# The crafter and the mothership animate, so they run _process. The command
+# centre is drawn once and never redrawn - per-frame redraws of art that
+# never changes were a real framerate cost earlier on.
+
+const MOTHERSHIP_COLOR: Color = Color(0.45, 0.9, 0.55)
+const CRAFTER_COLOR: Color = Color(1.0, 0.72, 0.25)
+const COMMAND_COLOR: Color = Color(0.55, 0.6, 1.0)
+const TRANSPORT_HUB_COLOR: Color = Color(0.95, 0.55, 0.85)
+const SHIP_LAB_COLOR: Color = Color(0.55, 0.95, 0.9)
+
+# Ship lab: a test frame with a vessel held in it and instruments sweeping
+# over it. Reads as a workshop rather than a factory - the crafter already
+# owns "assembly line", so this is measurement, not production.
+const LAB_FRAME_W: float = 78.0
+const LAB_FRAME_H: float = 58.0
+const LAB_MOUNT_RADIUS: float = 15.0
+const LAB_SCANNER_ORBIT: float = 96.0
+const LAB_SCAN_SPEED: float = 0.9
+
+# Transport hub: an octagonal dock ring with berths around it and a freight
+# core in the middle. Deliberately radial-but-flat, so it does not read as a
+# small mothership - the mothership is the only thing with swept arms.
+const HUB_RING_RADIUS: float = 74.0
+const HUB_DECK_RADIUS: float = 54.0
+const HUB_CORE_RADIUS: float = 22.0
+const HUB_BERTH_COUNT: int = 8
+const HUB_BERTH_LENGTH: float = 20.0
+const HUB_DOCKED_COUNT: int = 3
+const HUB_DOCKED_ORBIT: float = 96.0
+const HUB_SPIN_SPEED: float = 0.22
+# The vessel on the assembly line is drawn in the fleet's own colour, so it
+# reads as "one of yours being built" rather than as shipyard machinery.
+const HULL_COLOR: Color = Color(0.25, 0.85, 1.0)
+
+# One assembly cycle: parts are welded on, the finished hull flashes, then
+# it clears the cradle and the line starts over.
+const CYCLE: float = 3.6
+const ASSEMBLE_END: float = 0.66   # fraction of CYCLE spent welding
+const FLASH_END: float = 0.76      # ... then the completion flash
+                                   # ... then launch, to 1.0
+
+const CORE_CENTRE: Vector2 = Vector2(-58.0, 12.0)
+const BAY_CENTRE: Vector2 = Vector2(46.0, 12.0)
+const RIB_RADIUS: float = 36.0
+const RAIL_Y: float = -32.0
+const FLASH_RING_RADIUS: float = 20.0
+
+# The hull in four pieces, attached in this order. Each carries the point
+# the crane welds it on at, which is where the sparks fly from.
+const SHIP_PARTS: Array = [
+	{"at": 0.04, "weld": Vector2(0, -12), "points": [Vector2(0, -26), Vector2(-8, 4), Vector2(8, 4)]},
+	{"at": 0.28, "weld": Vector2(-13, 7), "points": [Vector2(-8, -4), Vector2(-22, 14), Vector2(-8, 10)]},
+	{"at": 0.48, "weld": Vector2(13, 7), "points": [Vector2(8, -4), Vector2(22, 14), Vector2(8, 10)]},
+	{"at": 0.70, "weld": Vector2(0, 10), "points": [Vector2(-7, 4), Vector2(7, 4), Vector2(5, 14), Vector2(-5, 14)]},
+]
+
+# The assembly clock, wrapped at CYCLE because the whole build sequence is
+# expressed as a fraction of it.
+var anim_time: float = 0.0
+
+# Free-running seconds for everything that is merely cyclic - reactor pulses,
+# orbiting satellites, blinking beacons. These must NOT share anim_time:
+# CYCLE is 3.6s, which is not a whole number of periods for any of them, so
+# wrapping made every one of them leap at the wrap. The satellites were the
+# obvious casualty, snapping back 66 degrees every 3.6 seconds.
+#
+# Deliberately never wrapped. GDScript floats are 64-bit, so even after hours
+# of play the argument to sin() keeps far more precision than a frame needs,
+# and any wrap point would reintroduce exactly the discontinuity above.
+var phase_time: float = 0.0
+
+var _hull_parts: Array[PackedVector2Array] = []
+
+# Every moving element is its own NeonPiece, rasterised once when the
+# building is created and thereafter only moved, scaled, faded or hidden.
+# Nothing here ever calls queue_redraw() again: the building's own _draw()
+# lays down the fixed structure a single time, and the animation is pure
+# node-property work from then on.
+var _core_cell: NeonPiece = null
+var _satellites: Node2D = null
+var _beacons: Array = []
+var _clamps: NeonPiece = null
+var _crane: Node2D = null
+var _hoist: NeonPiece = null
+var _sparks: Node2D = null
+var _hull_holder: Node2D = null
+var _hull_pieces: Array = []
+# Rotating holder for the transports stationed at a transport hub (#18).
+var _hub_traffic: Node2D = null
+# Sweeping instrument booms at a ship lab (#5).
+var _lab_scanners: Node2D = null
+var _flash_ring: NeonPiece = null
+var _wash: NeonPiece = null
+
+
+func _process(delta: float) -> void:
+	anim_time = fmod(anim_time + delta, CYCLE)
+	phase_time += delta
+	apply_animation()
+
+
+# Pushes the current clock onto the movable pieces. Normally driven from
+# _process; public so a preview or a test can pin the clock and see exactly
+# that frame without having to run the animation up to it in real time.
+func apply_animation() -> void:
+	pass
+
+
+# Where the satellites are, and how open the reactor core is. Both are read
+# by _draw and by the test that checks they stay continuous across the
+# assembly clock's wrap.
+func orbit_angle() -> float:
+	return phase_time * ORBIT_SPEED
+
+
+func core_pulse() -> float:
+	return 0.5 + 0.5 * sin(phase_time * PULSE_SPEED)
+
+
+# How many times this building's geometry has actually been rasterised. The
+# whole point of the NeonPiece decomposition is that this stays at 1 for the
+# building's lifetime however long it animates, so it is worth being able to
+# assert rather than assume.
+var draw_count: int = 0
+
+
+func register_draw() -> void:
+	draw_count += 1
+
+
+# --- shared helpers -------------------------------------------------------
+
+func _ring(centre: Vector2, radius: float, sides: int, phase: float = 0.0) -> PackedVector2Array:
+	var pts: PackedVector2Array = PackedVector2Array()
+	for i in range(sides):
+		var a: float = (float(i) / float(sides)) * TAU + phase
+		pts.append(centre + Vector2(cos(a), sin(a)) * radius)
+	return pts
+
+
+func _arc(centre: Vector2, radius: float, from_a: float, to_a: float, steps: int) -> PackedVector2Array:
+	var pts: PackedVector2Array = PackedVector2Array()
+	for i in range(steps + 1):
+		var a: float = lerpf(from_a, to_a, float(i) / float(steps))
+		pts.append(centre + Vector2(cos(a), sin(a)) * radius)
+	return pts
+
+
+
+
+# --- command centre: a tactical plotting hub ------------------------------
+# The mothership is radial-and-swept, the crafter is an asymmetric assembly
+# line, so the command centre reads best as the odd one out: rigid, hexagonal,
+# a wheel rather than a claw. Six spokes tie a hex rim to a central diamond
+# readout, and every spoke ends in a formation port - half of them holding a
+# token, half left open - so the structure itself shows fleet slots waiting
+# to be filled, which is exactly what the drag-and-drop editor inside does.
+
+const CMD_HEX_RADIUS: float = 88.0
+const CMD_DECK_RADIUS: float = 66.0
+const CMD_HUB_RADIUS: float = 30.0
+const CMD_SCREEN_RADIUS: float = 14.0
+const CMD_PORT_COUNT: int = 6
+const CMD_PORT_LENGTH: float = 16.0
+const CMD_TOKEN_RADIUS: float = 9.0
+const CMD_STUD_RADIUS: float = 7.0
+
+
+# --- ship lab -------------------------------------------------------------
+
+func _draw_ship_lab_static(target: CanvasItem) -> void:
+	var c: Color = SHIP_LAB_COLOR
+
+	# Outer test frame, open at the corners so it reads as a rig rather than
+	# a solid hull.
+	for sx in [-1.0, 1.0]:
+		for sy in [-1.0, 1.0]:
+			var corner: Vector2 = Vector2(sx * LAB_FRAME_W, sy * LAB_FRAME_H)
+			NeonDraw.draw_glowing_line(target, corner,
+				corner - Vector2(sx * LAB_FRAME_W * 0.45, 0.0), c, 0.9, 0.42)
+			NeonDraw.draw_glowing_line(target, corner,
+				corner - Vector2(0.0, sy * LAB_FRAME_H * 0.5), c, 0.9, 0.42)
+
+	# The vessel under test, held nose-up in the middle - deliberately the
+	# fleet's own silhouette, so it is obvious what the lab is for.
+	NeonDraw.draw_glowing_polygon(target, PackedVector2Array([
+		Vector2(0, -26), Vector2(13, 12), Vector2(0, 5), Vector2(-13, 12),
+	]), HULL_COLOR, 0.95)
+
+	# Mount ring and its bracing.
+	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, LAB_MOUNT_RADIUS, 6, PI / 6.0), c, 0.5,
+		NeonDraw.DEFAULT_CORE, 0.7)
+	for i in range(4):
+		var a: float = (float(i) / 4.0) * TAU + PI / 4.0
+		var dir: Vector2 = Vector2(cos(a), sin(a))
+		NeonDraw.draw_glowing_line(target, dir * LAB_MOUNT_RADIUS, dir * 40.0, c, 0.45, 0.3)
+
+
+func _build_lab_pieces() -> void:
+	# Two instrument booms sweeping round the vessel. One holder, rasterised
+	# once, rotated per frame (#10).
+	_lab_scanners = Node2D.new()
+	add_child(_lab_scanners)
+	for i in range(2):
+		var a: float = float(i) * PI
+		var at: Vector2 = Vector2(cos(a), sin(a)) * LAB_SCANNER_ORBIT
+		var piece: NeonPiece = NeonPiece.create(_lab_scanners, at, SHIP_LAB_COLOR)
+		piece.add_polygon(PackedVector2Array([
+			Vector2(-4, -12), Vector2(4, -12), Vector2(4, 12), Vector2(-4, 12),
+		]))
+		piece.add_line(Vector2(0, 0), Vector2(-cos(a), -sin(a)) * 26.0, 0.3, 0.5)
+		piece.rotation = a
+		piece.queue_redraw()
+
+
+func _animate_ship_lab() -> void:
+	_lab_scanners.rotation = phase_time * LAB_SCAN_SPEED
+
+
+# --- transport hub --------------------------------------------------------
+
+func _draw_transport_hub_static(target: CanvasItem) -> void:
+	var c: Color = TRANSPORT_HUB_COLOR
+
+	# Dock ring and the deck nested inside it.
+	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, HUB_RING_RADIUS, HUB_BERTH_COUNT, PI / 8.0), c, 1.0)
+	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, HUB_DECK_RADIUS, HUB_BERTH_COUNT, PI / 8.0), c, 0.45, NeonDraw.DEFAULT_CORE, 0.7)
+
+	# Freight core: a squared-off hold rather than a reactor, so it reads as
+	# storage and not as another power plant.
+	NeonDraw.draw_glowing_polygon(target, _ring(Vector2.ZERO, HUB_CORE_RADIUS, 4, PI / 4.0), c, 0.95)
+
+	for i in range(HUB_BERTH_COUNT):
+		var a: float = (float(i) / HUB_BERTH_COUNT) * TAU + PI / 8.0
+		var dir: Vector2 = Vector2(cos(a), sin(a))
+		NeonDraw.draw_glowing_line(target, dir * HUB_CORE_RADIUS, dir * HUB_DECK_RADIUS, c, 0.5, 0.32)
+		# Berth arm standing off the ring, where a transporter parks.
+		NeonDraw.draw_glowing_line(target, dir * HUB_RING_RADIUS,
+			dir * (HUB_RING_RADIUS + HUB_BERTH_LENGTH), c, 0.75, 0.38)
+
+
+func _build_hub_pieces() -> void:
+	# Stationed transports, as NeonPiece children of one holder that turns.
+	# Per #10 the geometry is rasterised once and only the holder's rotation
+	# changes, so the traffic costs no redraws at all.
+	_hub_traffic = Node2D.new()
+	add_child(_hub_traffic)
+	for i in range(HUB_DOCKED_COUNT):
+		var a: float = (float(i) / HUB_DOCKED_COUNT) * TAU
+		var at: Vector2 = Vector2(cos(a), sin(a)) * HUB_DOCKED_ORBIT
+		var piece: NeonPiece = NeonPiece.create(_hub_traffic, at, TRANSPORT_HUB_COLOR)
+		# A stubby freighter: blunt, boxy, nothing like the fleet's darts.
+		piece.add_polygon(PackedVector2Array([
+			Vector2(-9, -5), Vector2(9, -5), Vector2(12, 0), Vector2(9, 5), Vector2(-9, 5),
+		]))
+		piece.rotation = a + PI / 2.0
+		piece.queue_redraw()
+
+
+func _animate_transport_hub() -> void:
+	_hub_traffic.rotation = phase_time * HUB_SPIN_SPEED
+
+
+func _diamond(centre: Vector2, r: float) -> PackedVector2Array:
+	return PackedVector2Array([
+		centre + Vector2(0, -r), centre + Vector2(r, 0),
+		centre + Vector2(0, r), centre + Vector2(-r, 0),
+	])
+
+
+func _draw_command_center() -> void:
+	var c: Color = COMMAND_COLOR
+	var readout: Color = Color(0.82, 0.86, 1.0)
+
+	# The rim: a hex table holding the whole layout together, with a fainter
+	# deck ring nested just inside it - the same "plating has layers" read the
+	# mothership gets from its nested reactor rings.
+	NeonDraw.draw_glowing_polygon(self, _ring(Vector2.ZERO, CMD_HEX_RADIUS, CMD_PORT_COUNT, PI / 6.0), c, 1.0)
+	NeonDraw.draw_glowing_polygon(self, _ring(Vector2.ZERO, CMD_DECK_RADIUS, CMD_PORT_COUNT, PI / 6.0), c, 0.5, NeonDraw.DEFAULT_CORE, 0.7)
+
+	for i in range(CMD_PORT_COUNT):
+		var a: float = (float(i) / CMD_PORT_COUNT) * TAU + PI / 6.0
+		var dir: Vector2 = Vector2(cos(a), sin(a))
+		# Spoke bracing the hub to the rim.
+		NeonDraw.draw_glowing_line(self, dir * CMD_HUB_RADIUS, dir * CMD_HEX_RADIUS, c, 0.65, 0.36)
+		# Socket where the mast plugs into the rim.
+		NeonDraw.draw_glowing_polygon(self, _ring(dir * CMD_HEX_RADIUS, CMD_STUD_RADIUS, 6, a), c, 0.85)
+		# Port mast standing proud of the rim; every other one is manned.
+		var port_tip: Vector2 = dir * (CMD_HEX_RADIUS + CMD_PORT_LENGTH)
+		NeonDraw.draw_glowing_line(self, dir * CMD_HEX_RADIUS, port_tip, c, 0.8, 0.4)
+		if i % 2 == 0:
+			NeonDraw.draw_glowing_polygon(self, _diamond(port_tip, CMD_TOKEN_RADIUS), c, 1.0)
+
+	# Command core: a diamond hub with a lit readout set inside it.
+	NeonDraw.draw_glowing_polygon(self, _diamond(Vector2.ZERO, CMD_HUB_RADIUS), c, 1.0)
+	NeonDraw.draw_glowing_polygon(self, _diamond(Vector2.ZERO, CMD_SCREEN_RADIUS), readout, 0.9)
+
+
+# --- mothership: a radial flagship ----------------------------------------
+# Not a big fighter. A mothership is the thing everything else orbits, so it
+# is built radially around a reactor core rather than pointed in a direction:
+# six swept talons, crystal panels set between them, and satellites circling
+# the whole assembly. A forward-facing hull, however large, just reads as
+# another ship.
+
+const ARM_COUNT: int = 6
+const ARM_INNER: float = 42.0
+const ARM_OUTER: float = 106.0
+const ARM_SWEEP: float = 0.72
+const SATELLITE_COUNT: int = 4
+const SATELLITE_ORBIT: float = 126.0
+const ORBIT_SPEED: float = 0.32
+const PULSE_SPEED: float = 2.4
+
+
+func _talon(base_angle: float) -> PackedVector2Array:
+	# One swept claw: the outer edge runs from the core to the tip, and the
+	# inner edge comes back a little behind it, closing to a point so the arm
+	# tapers instead of ending in a blunt stub.
+	var steps: int = 7
+	var pts: PackedVector2Array = PackedVector2Array()
+	for i in range(steps + 1):
+		var f: float = float(i) / float(steps)
+		var a: float = base_angle + ARM_SWEEP * pow(f, 1.3)
+		pts.append(Vector2(cos(a), sin(a)) * lerpf(ARM_INNER, ARM_OUTER, f))
+	for i in range(steps, -1, -1):
+		var f: float = float(i) / float(steps)
+		var trail: float = 0.34 * (1.0 - f) + 0.04
+		var a: float = base_angle + ARM_SWEEP * pow(f, 1.3) - trail
+		pts.append(Vector2(cos(a), sin(a)) * lerpf(ARM_INNER, ARM_OUTER, f))
+	return pts
+
+
+func _draw_mothership_static(canvas: CanvasItem) -> void:
+	var c: Color = MOTHERSHIP_COLOR
+	for i in range(ARM_COUNT):
+		var base: float = (float(i) / float(ARM_COUNT)) * TAU
+		NeonDraw.draw_glowing_polygon(canvas, _talon(base), c, 0.95)
+		# Crystal panel set into the gap behind each arm.
+		var pa: float = base - 0.30
+		NeonDraw.draw_glowing_polygon(canvas, PackedVector2Array([
+			Vector2(cos(pa - 0.11), sin(pa - 0.11)) * 54.0,
+			Vector2(cos(pa + 0.11), sin(pa + 0.11)) * 54.0,
+			Vector2(cos(pa + 0.15), sin(pa + 0.15)) * 86.0,
+			Vector2(cos(pa - 0.15), sin(pa - 0.15)) * 86.0,
+		]), c, 0.7)
+
+	# Reactor housing: the nested rings around the cell that breathes.
+	NeonDraw.draw_glowing_polygon(canvas, _ring(Vector2.ZERO, 38.0, 6, PI / 6.0), c, 1.0)
+	NeonDraw.draw_glowing_polygon(canvas, _ring(Vector2.ZERO, 24.0, 6, 0.0), c, 0.85)
+
+
+const CORE_CELL_RADIUS: float = 12.0
+
+
+func _build_mothership_pieces() -> void:
+	var core_color: Color = Color(0.75, 1.0, 0.85)
+
+	# The breathing cell: drawn at a reference size and then scaled, rather
+	# than rebuilt at a new radius every frame.
+	_core_cell = NeonPiece.create(self, Vector2.ZERO, core_color)
+	_core_cell.add_polygon(_ring(Vector2.ZERO, CORE_CELL_RADIUS, 6, PI / 6.0))
+
+	# Satellites sit at fixed offsets inside a holder; the orbit is the
+	# holder's rotation, so four hexagon pairs become one transform update.
+	_satellites = Node2D.new()
+	add_child(_satellites)
+	for i in range(SATELLITE_COUNT):
+		var a: float = (float(i) / float(SATELLITE_COUNT)) * TAU
+		var at: Vector2 = Vector2(cos(a), sin(a)) * SATELLITE_ORBIT
+		var shell: NeonPiece = NeonPiece.create(_satellites, at, MOTHERSHIP_COLOR)
+		shell.add_polygon(_ring(Vector2.ZERO, 10.0, 6, PI / 6.0), 0.85)
+		var cell: NeonPiece = NeonPiece.create(_satellites, at, core_color)
+		cell.add_polygon(_ring(Vector2.ZERO, 4.5, 6, PI / 6.0), 0.8)
+
+
+func _animate_mothership() -> void:
+	var breath: float = core_pulse()
+	var radius: float = lerpf(9.0, 15.0, breath)
+	_core_cell.scale = Vector2.ONE * (radius / CORE_CELL_RADIUS)
+	_core_cell.modulate.a = lerpf(0.55, 1.0, breath)
+	_satellites.rotation = orbit_angle()
+
+
+# --- ship crafter: an orbital yard with a hull in the cradle --------------
+
+func _draw_crafter_static(canvas: CanvasItem) -> void:
+	var c: Color = CRAFTER_COLOR
+
+	# Fabricator core housing. This replaces the chimney - nothing vents
+	# smoke in vacuum.
+	NeonDraw.draw_glowing_polygon(canvas, _ring(CORE_CENTRE, 26.0, 6, PI / 6.0), c, 1.0)
+
+	# Radiator fins above and below the core, slatted like real ones.
+	for dir_y in [-1.0, 1.0]:
+		var fin: PackedVector2Array = PackedVector2Array([
+			CORE_CENTRE + Vector2(-16, 30 * dir_y), CORE_CENTRE + Vector2(18, 34 * dir_y),
+			CORE_CENTRE + Vector2(24, 54 * dir_y), CORE_CENTRE + Vector2(-10, 50 * dir_y),
+		])
+		NeonDraw.draw_glowing_polygon(canvas, fin, c, 0.75)
+		for f in [0.35, 0.68]:
+			NeonDraw.draw_glowing_line(canvas,
+				fin[0].lerp(fin[3], f), fin[1].lerp(fin[2], f), c, 0.5, 0.28)
+
+	# Truss spine linking the core to the cradle: two rails with X-bracing,
+	# the standard "this was assembled in orbit" read.
+	var spine_top: float = 4.0
+	var spine_bottom: float = 22.0
+	NeonDraw.draw_glowing_line(canvas, Vector2(-32, spine_top), Vector2(14, spine_top), c, 0.9, 0.4)
+	NeonDraw.draw_glowing_line(canvas, Vector2(-32, spine_bottom), Vector2(14, spine_bottom), c, 0.9, 0.4)
+	for i in range(3):
+		var x0: float = -32.0 + float(i) * 15.0
+		var x1: float = x0 + 15.0
+		NeonDraw.draw_glowing_line(canvas, Vector2(x0, spine_top), Vector2(x1, spine_bottom), c, 0.55, 0.28)
+		NeonDraw.draw_glowing_line(canvas, Vector2(x0, spine_bottom), Vector2(x1, spine_top), c, 0.55, 0.28)
+
+	# Construction cradle: two open ribs holding the hull, with the crane
+	# rail overhead. Open at the top so the finished hull can clear it.
+	NeonDraw.draw_glowing_path(canvas, _arc(BAY_CENTRE, RIB_RADIUS, 2.10, 4.18, 7), c, 1.0, 0.7)
+	NeonDraw.draw_glowing_path(canvas, _arc(BAY_CENTRE, RIB_RADIUS, -1.04, 1.04, 7), c, 1.0, 0.7)
+	NeonDraw.draw_glowing_line(canvas, Vector2(10, RAIL_Y), Vector2(82, RAIL_Y), c, 0.9, 0.55)
+	for side in [-1.0, 1.0]:
+		NeonDraw.draw_glowing_line(canvas,
+			BAY_CENTRE + Vector2(RIB_RADIUS * side, -6.0), Vector2(BAY_CENTRE.x + 44.0 * side, RAIL_Y), c, 0.7, 0.3)
+
+
+
+func _build_crafter_pieces() -> void:
+	var c: Color = CRAFTER_COLOR
+
+	# The core's inner cell: fades with the reactor rather than being redrawn
+	# at a new brightness each frame.
+	_core_cell = NeonPiece.create(self, CORE_CENTRE, Color(1.0, 0.9, 0.6))
+	_core_cell.add_polygon(_ring(Vector2.ZERO, 12.0, 6, PI / 6.0))
+
+	# Docking beacons, blinking out of step with each other.
+	for i in range(2):
+		var lamp: Vector2 = BAY_CENTRE + Vector2(-RIB_RADIUS + 2.0 + float(i) * (RIB_RADIUS * 2.0 - 4.0), 30.0)
+		var beacon: NeonPiece = NeonPiece.create(self, lamp, Color(1.0, 0.95, 0.75))
+		beacon.add_polygon(_ring(Vector2.ZERO, 3.0, 4))
+		_beacons.append(beacon)
+
+	# Clamp arms reaching in from each rib. They let go as the hull launches,
+	# which is a fade rather than a redraw.
+	_clamps = NeonPiece.create(self, Vector2.ZERO, c)
+	for side in [-1.0, 1.0]:
+		var outer: Vector2 = BAY_CENTRE + Vector2(RIB_RADIUS * side, 6.0)
+		var inner: Vector2 = BAY_CENTRE + Vector2(24.0 * side, 6.0)
+		_clamps.add_line(outer, inner, 0.35)
+		_clamps.add_line(inner + Vector2(0, -5), inner + Vector2(0, 5), 0.3)
+
+	# Crane: the head rides the rail, so only its x moves. The hoist is drawn
+	# one unit long and stretched with scale.y to reach whatever seam is
+	# being welded - stretching a line needs no redraw, redrawing it would.
+	_crane = Node2D.new()
+	add_child(_crane)
+	var head: NeonPiece = NeonPiece.create(_crane, Vector2.ZERO, c)
+	head.add_polygon(PackedVector2Array([
+		Vector2(-10, -7), Vector2(10, -7), Vector2(6, 6), Vector2(-6, 6),
+	]))
+	head.add_line(Vector2(0, -7), Vector2(0, RAIL_Y - (RAIL_Y + 13.0)), 0.35, 0.8)
+	_hoist = NeonPiece.create(_crane, Vector2(0, 6), c, 0.5)
+	_hoist.add_line(Vector2.ZERO, Vector2(0, 1), 0.3)
+
+	# Weld sparks: four spokes on a holder that spins and stretches. The
+	# jitter is genuinely procedural, but rotating and scaling a holder gives
+	# the same flicker without re-tessellating the spokes every frame.
+	_sparks = Node2D.new()
+	add_child(_sparks)
+	for i in range(4):
+		var a: float = float(i) * TAU / 4.0
+		var spark: NeonPiece = NeonPiece.create(_sparks, Vector2.ZERO, Color(1.0, 0.95, 0.7))
+		spark.add_line(Vector2.ZERO, Vector2(cos(a), sin(a)) * 11.0, 0.3)
+
+	# The hull under construction. Each part is its own piece so attaching one
+	# is a `visible` flip, and the launch is the holder's position and alpha.
+	_hull_holder = Node2D.new()
+	add_child(_hull_holder)
+	for i in range(_hull_parts.size()):
+		var part: NeonPiece = NeonPiece.create(_hull_holder, Vector2.ZERO, HULL_COLOR)
+		part.add_polygon(_hull_parts[i])
+		part.visible = false
+		_hull_pieces.append(part)
+
+	# Engine wash under the hull, and the completion ring. The ring is drawn
+	# at a reference radius and scaled outwards.
+	_wash = NeonPiece.create(_hull_holder, Vector2.ZERO, Color(1.0, 0.85, 0.45), 0.0)
+	for dx in [-4.0, 4.0]:
+		_wash.add_line(Vector2(dx, 14), Vector2(dx * 1.6, 30.0), 0.45)
+
+	_flash_ring = NeonPiece.create(self, BAY_CENTRE, HULL_COLOR, 0.0)
+	_flash_ring.add_polygon(_ring(Vector2.ZERO, FLASH_RING_RADIUS, 6, PI / 6.0))
+
+
+func _animate_crafter() -> void:
+	var t: float = anim_time / CYCLE
+
+	_core_cell.modulate.a = 0.45 + 0.55 * (0.5 + 0.5 * sin(phase_time * 4.0))
+	for i in range(_beacons.size()):
+		_beacons[i].modulate.a = 0.15 + 0.45 * (0.5 + 0.5 * sin(phase_time * 6.0 + float(i) * PI))
+
+	if t < ASSEMBLE_END:
+		_animate_assembly(t / ASSEMBLE_END)
+	elif t < FLASH_END:
+		_animate_completion_flash((t - ASSEMBLE_END) / (FLASH_END - ASSEMBLE_END))
+	else:
+		_animate_launch((t - FLASH_END) / (1.0 - FLASH_END))
+
+
+# How many pieces are on the hull at this point through the assembly phase.
+# Parts attach in order, so this is just how many thresholds have passed.
+func attached_part_count(p: float) -> int:
+	var n: int = 0
+	for part in SHIP_PARTS:
+		if p >= float(part.at):
+			n += 1
+	return n
+
+
+func _place_hull(centre: Vector2, alpha: float) -> void:
+	# The parts are defined around their own origin, so the holder goes
+	# straight to the point they should be centred on.
+	_hull_holder.position = centre
+	_hull_holder.modulate.a = alpha
+
+
+func _animate_assembly(p: float) -> void:
+	_clamps.visible = true
+	_clamps.modulate.a = 0.8
+	_flash_ring.modulate.a = 0.0
+	_wash.modulate.a = 0.0
+	_place_hull(BAY_CENTRE, 1.0)
+
+	var next_part: int = attached_part_count(p)
+	for i in range(_hull_pieces.size()):
+		var attached: bool = i < next_part
+		_hull_pieces[i].visible = attached
+		if attached:
+			# Freshly attached parts flare, then settle to full brightness.
+			var age: float = p - float(SHIP_PARTS[i].at)
+			_hull_pieces[i].modulate.a = 1.0 if age > 0.08 else lerpf(0.3, 1.0, age / 0.08)
+
+	# The crane rides the rail over whichever seam is being worked, and
+	# retracts once there is nothing left to attach.
+	var weld: Vector2 = BAY_CENTRE + (SHIP_PARTS[mini(next_part, SHIP_PARTS.size() - 1)].weld as Vector2)
+	if next_part >= _hull_pieces.size():
+		weld.y = RAIL_Y + 16.0
+	_crane.position = Vector2(weld.x, RAIL_Y + 13.0)
+	_hoist.scale.y = maxf(weld.y - (RAIL_Y + 19.0), 1.0)
+
+	var welding: bool = next_part < _hull_pieces.size()
+	_sparks.visible = welding
+	if welding:
+		var flicker: float = 0.45 + 0.55 * absf(sin(phase_time * 34.0))
+		_sparks.position = weld
+		_sparks.rotation = phase_time * 7.0
+		_sparks.scale = Vector2.ONE * (0.55 + 0.45 * flicker)
+		_sparks.modulate.a = flicker
+
+
+func _animate_completion_flash(p: float) -> void:
+	# Whole hull, clamps springing open, and a ring pushing outwards to mark
+	# it as finished.
+	_clamps.modulate.a = 1.0 - p
+	_sparks.visible = false
+	_place_hull(BAY_CENTRE, 1.0)
+	for piece in _hull_pieces:
+		piece.visible = true
+		piece.modulate.a = 1.0
+	# Retracted, so it does not hang over the finished hull.
+	_crane.position = Vector2(BAY_CENTRE.x, RAIL_Y + 13.0)
+	_hoist.scale.y = 1.0
+	_flash_ring.modulate.a = 1.0 - p
+	_flash_ring.scale = Vector2.ONE * (lerpf(18.0, 56.0, p) / FLASH_RING_RADIUS)
+
+
+func _animate_launch(p: float) -> void:
+	# Clears the cradle and fades out; the next cycle starts from bare ribs.
+	_clamps.modulate.a = 0.0
+	_sparks.visible = false
+	_flash_ring.modulate.a = 0.0
+	var eased: float = p * p
+	var fade: float = clampf(1.0 - p * 1.15, 0.0, 1.0)
+	_place_hull(BAY_CENTRE + Vector2(0.0, -124.0 * eased), fade)
+	for piece in _hull_pieces:
+		piece.visible = true
+		piece.modulate.a = 1.0
+	# Engine wash, strongest just after it breaks free of the clamps.
+	_wash.modulate.a = 0.4 + 0.6 * sin(minf(p * 3.2, PI))
diff --git a/BuildingVisualBase.gd.uid b/BuildingVisualBase.gd.uid
new file mode 100644
index 0000000..8827724
--- /dev/null
+++ b/BuildingVisualBase.gd.uid
@@ -0,0 +1 @@
+uid://p7vuv1xsksc
diff --git a/CommandBuildingDefinition.tres b/CommandBuildingDefinition.tres
new file mode 100644
index 0000000..727a6f4
--- /dev/null
+++ b/CommandBuildingDefinition.tres
@@ -0,0 +1,20 @@
+[gd_resource type="Resource" script_class="BuildingDefinition" load_steps=3 format=3]
+[ext_resource type="Script" path="res://BuildingDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://CommandBuildingVisual.tscn" id="2"]
+[resource]
+script = ExtResource("1")
+definition_id = "command_center"
+display_name = "Command Center"
+description = "Fly the fleet onto it to drag your fleet into a new formation. Rebuilt fleets keep it."
+cost = 15
+action_icon = 10
+menu_icon = 10
+visual_scene = ExtResource("2")
+capabilities = PackedStringArray("formation")
+map_color = Color(0.55, 0.6, 1, 1)
+map_sides = 4
+map_radius = 6.0
+map_phase = 0.785398
+menu_button_name = "CommandButton"
+menu_label_name = "CommandLabel"
+menu_cost_name = "CommandCost"
diff --git a/CommandBuildingVisual.gd b/CommandBuildingVisual.gd
new file mode 100644
index 0000000..713b407
--- /dev/null
+++ b/CommandBuildingVisual.gd
@@ -0,0 +1,9 @@
+extends "res://BuildingVisualBase.gd"
+
+func _ready() -> void:
+	set_process(false)
+	queue_redraw()
+
+func _draw() -> void:
+	register_draw()
+	_draw_command_center()
diff --git a/CommandBuildingVisual.gd.uid b/CommandBuildingVisual.gd.uid
new file mode 100644
index 0000000..9a270e2
--- /dev/null
+++ b/CommandBuildingVisual.gd.uid
@@ -0,0 +1 @@
+uid://bpb5pq8g56ywn
diff --git a/CommandBuildingVisual.tscn b/CommandBuildingVisual.tscn
new file mode 100644
index 0000000..048b3f3
--- /dev/null
+++ b/CommandBuildingVisual.tscn
@@ -0,0 +1,11 @@
+[gd_scene load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://CommandBuildingVisual.gd" id="1"]
+[ext_resource type="Script" path="res://BuildingActionProvider.gd" id="2"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
+
+[node name="ActionProvider" type="Node" parent="."]
+script = ExtResource("2")
+actions = PackedStringArray("formation", "transfer")
diff --git a/CrafterBuildingDefinition.tres b/CrafterBuildingDefinition.tres
new file mode 100644
index 0000000..2a3f91f
--- /dev/null
+++ b/CrafterBuildingDefinition.tres
@@ -0,0 +1,19 @@
+[gd_resource type="Resource" script_class="BuildingDefinition" load_steps=3 format=3]
+[ext_resource type="Script" path="res://BuildingDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://CrafterBuildingVisual.tscn" id="2"]
+[resource]
+script = ExtResource("1")
+definition_id = "ship_crafter"
+display_name = "Ship Crafter"
+description = "Fly the fleet onto it, then use the action button to build extra vessels."
+cost = 12
+action_icon = 2
+menu_icon = 9
+visual_scene = ExtResource("2")
+capabilities = PackedStringArray("production")
+map_color = Color(1, 0.72, 0.25, 1)
+map_sides = 4
+map_radius = 7.0
+menu_button_name = "CrafterButton"
+menu_label_name = "CrafterLabel"
+menu_cost_name = "CrafterCost"
diff --git a/CrafterBuildingVisual.gd b/CrafterBuildingVisual.gd
new file mode 100644
index 0000000..ddd41a8
--- /dev/null
+++ b/CrafterBuildingVisual.gd
@@ -0,0 +1,14 @@
+extends "res://BuildingVisualBase.gd"
+
+func _ready() -> void:
+	for part in SHIP_PARTS:
+		_hull_parts.append(PackedVector2Array(part.points))
+	_build_crafter_pieces()
+	queue_redraw()
+
+func apply_animation() -> void:
+	_animate_crafter()
+
+func _draw() -> void:
+	register_draw()
+	_draw_crafter_static(self)
diff --git a/CrafterBuildingVisual.gd.uid b/CrafterBuildingVisual.gd.uid
new file mode 100644
index 0000000..05576b0
--- /dev/null
+++ b/CrafterBuildingVisual.gd.uid
@@ -0,0 +1 @@
+uid://dbwebd1vf7biy
diff --git a/CrafterBuildingVisual.tscn b/CrafterBuildingVisual.tscn
new file mode 100644
index 0000000..c3bb670
--- /dev/null
+++ b/CrafterBuildingVisual.tscn
@@ -0,0 +1,11 @@
+[gd_scene load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://CrafterBuildingVisual.gd" id="1"]
+[ext_resource type="Script" path="res://BuildingActionProvider.gd" id="2"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
+
+[node name="ActionProvider" type="Node" parent="."]
+script = ExtResource("2")
+actions = PackedStringArray("craft", "transfer")
diff --git a/ExtractorBuildingDefinition.tres b/ExtractorBuildingDefinition.tres
new file mode 100644
index 0000000..0584758
--- /dev/null
+++ b/ExtractorBuildingDefinition.tres
@@ -0,0 +1,16 @@
+[gd_resource type="Resource" script_class="BuildingDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://BuildingDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+definition_id = "extractor"
+display_name = "Extractor"
+description = "Mines resources into local storage for transport vessels to collect. It keeps extracting while you are away."
+cost = 25
+action_icon = 11
+menu_icon = 11
+capabilities = PackedStringArray("extraction")
+map_color = Color(1, 0.85, 0.3, 1)
+menu_button_name = "ExtractorButton"
+menu_label_name = "ExtractorLabel"
+menu_cost_name = "ExtractorCost"
+placement_mode = "planet"
diff --git a/GameState.gd b/GameState.gd
index f855f2a..37d110a 100644
--- a/GameState.gd
+++ b/GameState.gd
@@ -1,5 +1,11 @@
 extends Node
 
+const INVENTORY = preload("res://Inventory.gd")
+const RESOURCE_DEFINITIONS = preload("res://ResourceDefinitions.gd")
+const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
+
 # Autoload singleton - the one thing that survives change_scene_to_file()
 # scene swaps between space (Main.tscn) and a planet's surface
 # (PlanetSurface.tscn). Everything else in either scene gets torn down
@@ -12,7 +18,7 @@ var return_world_position: Vector2 = Vector2.ZERO
 var return_camera_zoom: float = 1.0
 
 var planet_name: String = ""
-var planet_type: String = ""
+var planet_definition_id: String = "rocky"
 
 # Explored-chunk history for the world map's fog-of-war reveal. Lives
 # here (not on ExplorationTracker, which gets destroyed and recreated on
@@ -22,126 +28,101 @@ var explored_chunks: Dictionary = {}
 
 # --- Resources -------------------------------------------------------------
 
-# Ore that has been BANKED at the mothership. This is the only pool anything
-# can be bought with.
-# Starts stocked for play-testing so buildings can be tried without mining
-# first - drop this back to 0 for a real playthrough.
-var rocks: int = 500
+const RESOURCE_ORE: String = RESOURCE_DEFINITIONS.ORE_ID
+const RESOURCE_GAS: String = RESOURCE_DEFINITIONS.GAS_ID
+const RESOURCE_TYPES: PackedStringArray = RESOURCE_DEFINITIONS.ORDER
 
-# Gas is a second, banked resource. It is deliberately separate from ore:
-# construction still spends ore, while future gas technologies can consume
-# gas without making the two materials silently interchangeable.
-var gas: int = 0
+# All resource-bearing locations use the same container. The old public
+# names below are computed compatibility accessors, not separate storage.
+var bank_inventory: RefCounted = INVENTORY.new({RESOURCE_ORE: 500})
+var fleet_inventory: RefCounted = INVENTORY.new()
 
-# Ore the fleet is physically carrying and has not delivered yet (#14). Mining
-# fills this, not `rocks`: ore is cargo until the fleet brings it home, so a
-# long mining run is a real trip with something to lose rather than instant
-# income from anywhere on the map.
-#
-# Lives here, like everything else that has to survive Main.tscn being torn
-# down and rebuilt on every trip to a planet's surface - and cargo mined ON a
-# surface would otherwise be dropped the moment the player took off.
-var fleet_cargo: int = 0
-var fleet_gas_cargo: int = 0
+var rocks: int:
+	get: return bank_inventory.amount(RESOURCE_ORE)
+	set(value): bank_inventory.set_amount(RESOURCE_ORE, value)
 
-# Resource-facing UI and logistics iterate this list instead of growing a
-# second set of controls and controller branches every time a material is
-# introduced. Keep presentation data here with the state it describes so a
-# resource has one name and colour everywhere it appears.
-const RESOURCE_ORE: String = "ore"
-const RESOURCE_GAS: String = "gas"
-const RESOURCE_TYPES: PackedStringArray = [RESOURCE_ORE, RESOURCE_GAS]
-const RESOURCE_NAMES: Dictionary = {
-	RESOURCE_ORE: "Ore",
-	RESOURCE_GAS: "Gas",
-}
-const RESOURCE_COLORS: Dictionary = {
-	RESOURCE_ORE: Color(0.0, 0.72, 0.82),
-	RESOURCE_GAS: Color(0.85, 0.52, 1.0),
-}
+var gas: int:
+	get: return bank_inventory.amount(RESOURCE_GAS)
+	set(value): bank_inventory.set_amount(RESOURCE_GAS, value)
+
+var fleet_cargo: int:
+	get: return fleet_inventory.amount(RESOURCE_ORE)
+	set(value): fleet_inventory.set_amount(RESOURCE_ORE, value)
+
+var fleet_gas_cargo: int:
+	get: return fleet_inventory.amount(RESOURCE_GAS)
+	set(value): fleet_inventory.set_amount(RESOURCE_GAS, value)
 
 func collect_cargo(amount: int = 1) -> void:
-	fleet_cargo += amount
+	fleet_inventory.deposit(RESOURCE_ORE, amount)
 
 func collect_gas_cargo(amount: int = 1) -> void:
-	fleet_gas_cargo += amount
+	fleet_inventory.deposit(RESOURCE_GAS, amount)
+
+
+func resource_types() -> PackedStringArray:
+	return RESOURCE_DEFINITIONS.ids()
+
+
+func resource_definition(resource_type: String) -> Resource:
+	return RESOURCE_DEFINITIONS.get_definition(resource_type)
 
 
 func resource_name(resource_type: String) -> String:
-	return String(RESOURCE_NAMES.get(resource_type, resource_type.capitalize()))
+	var definition: Resource = resource_definition(resource_type)
+	return String(definition.display_name) if definition != null else resource_type.capitalize()
 
 
 func resource_color(resource_type: String) -> Color:
-	return RESOURCE_COLORS.get(resource_type, Color.WHITE)
+	var definition: Resource = resource_definition(resource_type)
+	return definition.color if definition != null else Color.WHITE
 
 
 func banked_resource(resource_type: String) -> int:
-	match resource_type:
-		RESOURCE_ORE: return rocks
-		RESOURCE_GAS: return gas
-		_: return 0
+	return bank_inventory.amount(resource_type)
 
 
 func fleet_resource(resource_type: String) -> int:
-	match resource_type:
-		RESOURCE_ORE: return fleet_cargo
-		RESOURCE_GAS: return fleet_gas_cargo
-		_: return 0
+	return fleet_inventory.amount(resource_type)
+
+
+func _inventory_for_record(record: Dictionary) -> RefCounted:
+	var inventory: RefCounted = record.get("inventory") as RefCounted
+	if inventory == null:
+		inventory = INVENTORY.new()
+		record.inventory = inventory
+	# Compatibility migration for state made before #33. Erase each legacy
+	# field once absorbed so it cannot drift out of step with the inventory.
+	if record.has("stock"):
+		inventory.set_amount(RESOURCE_ORE, int(record.stock))
+		record.erase("stock")
+	if record.has("gas_stock"):
+		inventory.set_amount(RESOURCE_GAS, int(record.gas_stock))
+		record.erase("gas_stock")
+	return inventory
+
+
+func building_inventory(id: int) -> RefCounted:
+	var building: Dictionary = find_building(id)
+	if building.is_empty():
+		return null
+	if building_has_capability(building, "bank"):
+		return bank_inventory
+	return _inventory_for_record(building)
 
 
 func building_resource(id: int, resource_type: String) -> int:
-	var building: Dictionary = find_building(id)
-	if building.is_empty():
-		return 0
-	if building.type == BUILDING_MOTHERSHIP:
-		return banked_resource(resource_type)
-	match resource_type:
-		RESOURCE_ORE: return int(building.get("stock", 0))
-		RESOURCE_GAS: return int(building.get("gas_stock", 0))
-		_: return 0
+	var inventory: RefCounted = building_inventory(id)
+	return 0 if inventory == null else inventory.amount(resource_type)
 
 
 func transfer_resource_to_building(id: int, resource_type: String, amount: int) -> int:
-	var building: Dictionary = find_building(id)
-	if building.is_empty():
-		return 0
-	var moved: int = mini(maxi(amount, 0), fleet_resource(resource_type))
-	if moved <= 0:
-		return 0
-	match resource_type:
-		RESOURCE_ORE: fleet_cargo -= moved
-		RESOURCE_GAS: fleet_gas_cargo -= moved
-		_: return 0
-	if building.type == BUILDING_MOTHERSHIP:
-		match resource_type:
-			RESOURCE_ORE: rocks += moved
-			RESOURCE_GAS: gas += moved
-	else:
-		match resource_type:
-			RESOURCE_ORE: building.stock = int(building.get("stock", 0)) + moved
-			RESOURCE_GAS: building.gas_stock = int(building.get("gas_stock", 0)) + moved
-	return moved
+	return fleet_inventory.transfer_to(building_inventory(id), resource_type, amount)
 
 
 func transfer_resource_to_fleet(id: int, resource_type: String, amount: int) -> int:
-	var building: Dictionary = find_building(id)
-	if building.is_empty():
-		return 0
-	var moved: int = mini(maxi(amount, 0), building_resource(id, resource_type))
-	if moved <= 0:
-		return 0
-	if building.type == BUILDING_MOTHERSHIP:
-		match resource_type:
-			RESOURCE_ORE: rocks -= moved
-			RESOURCE_GAS: gas -= moved
-	else:
-		match resource_type:
-			RESOURCE_ORE: building.stock = int(building.get("stock", 0)) - moved
-			RESOURCE_GAS: building.gas_stock = int(building.get("gas_stock", 0)) - moved
-	match resource_type:
-		RESOURCE_ORE: fleet_cargo += moved
-		RESOURCE_GAS: fleet_gas_cargo += moved
-	return moved
+	var source: RefCounted = building_inventory(id)
+	return 0 if source == null else source.transfer_to(fleet_inventory, resource_type, amount)
 
 
 # The batch size the transfer menu offers, next to "All". A batch rather
@@ -334,11 +315,6 @@ func unlock(id: String) -> bool:
 
 
 func is_building_unlocked(type: String) -> bool:
-	# The mothership is always buildable: it is where research happens, so
-	# locking it would leave a player with no mothership unable to ever get
-	# one.
-	if type == BUILDING_MOTHERSHIP:
-		return true
 	for node in SKILL_TREE:
 		if node.get("unlocks", "") == type:
 			return is_unlocked(node.id)
@@ -400,8 +376,8 @@ func add_building(type: String, at_position: Vector2) -> int:
 	var id: int = next_building_id
 	next_building_id += 1
 	buildings.append({
-		"id": id, "type": type, "position": at_position, "stock": 0,
-		"gas_stock": 0, "orders": [],
+		"id": id, "type": type, "position": at_position,
+		"inventory": INVENTORY.new(), "orders": [],
 	})
 	return id
 
@@ -413,6 +389,13 @@ func find_building(id: int) -> Dictionary:
 	return {}
 
 
+func building_has_capability(building: Dictionary, capability: String) -> bool:
+	if building.is_empty():
+		return false
+	var definition: Resource = BUILDING_DEFINITIONS.get_definition(String(building.type))
+	return definition != null and capability in definition.capabilities
+
+
 # --- vessel types and their upgrades (#5) ---------------------------------
 
 # The three things that can be flying around. The first and last double as
@@ -422,21 +405,10 @@ const VESSEL_INTERCEPTOR: String = "interceptor"
 const VESSEL_SHIELD: String = "shield"
 const VESSEL_TRANSPORTER: String = "transporter"
 
-const VESSEL_NAMES: Dictionary = {
-	VESSEL_INTERCEPTOR: "Interceptor",
-	VESSEL_SHIELD: "Shield Vessel",
-	VESSEL_TRANSPORTER: "Transporter",
-}
-
+# Compatibility constants for callers and old tests. Runtime metadata is
+# resolved from VesselDefinition below.
 const SHIELD_COST: int = 14
-
-# How long one vessel takes to build, once its ore is actually in the
-# building. A queue you can watch and cancel needs time to exist in.
-const BUILD_TIMES: Dictionary = {
-	VESSEL_INTERCEPTOR: 10.0,
-	VESSEL_SHIELD: 16.0,
-	VESSEL_TRANSPORTER: 8.0,
-}
+const TRANSPORTER_COST: int = 10
 const LAB_RESEARCH_TIME: float = 8.0
 
 
@@ -447,57 +419,14 @@ var build_time_scale: float = 1.0
 
 
 func build_time(product: String) -> float:
-	return float(BUILD_TIMES.get(product, 10.0)) * build_time_scale
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(product)
+	return (definition.build_time if definition != null else 10.0) * build_time_scale
 
 
 func lab_research_time() -> float:
 	return LAB_RESEARCH_TIME * build_time_scale
 
-# Researched at the ship lab, per vessel type. Separate from SKILL_TREE on
-# purpose: that gates what the player may build at all and is a strategic
-# spine, while these are repeatable tuning on a vessel you already have.
-# `cost` is the FIRST level; each level after costs cost * (level + 1), so
-# the third point in something is not the same price as the first.
-const VESSEL_UPGRADES: Array = [
-	{
-		"id": "int_damage", "vessel": VESSEL_INTERCEPTOR, "name": "Heavy Slugs",
-		"cost": 30, "max_level": 3, "desc": "+1 damage per shot.",
-	},
-	{
-		"id": "int_rate", "vessel": VESSEL_INTERCEPTOR, "name": "Autoloader",
-		"cost": 25, "max_level": 3, "desc": "Fires 15% faster per level.",
-	},
-	{
-		"id": "int_range", "vessel": VESSEL_INTERCEPTOR, "name": "Targeting Array",
-		"cost": 20, "max_level": 3, "desc": "+60 firing range per level.",
-	},
-	{
-		"id": "int_speed", "vessel": VESSEL_INTERCEPTOR, "name": "Thrusters",
-		"cost": 25, "max_level": 3, "desc": "+40 top speed, +60 acceleration per level.",
-	},
-	{
-		"id": "shd_hits", "vessel": VESSEL_SHIELD, "name": "Layered Emitters",
-		"cost": 60, "max_level": 2, "desc": "+1 hit absorbed before the shield drops.",
-	},
-	{
-		"id": "shd_recharge", "vessel": VESSEL_SHIELD, "name": "Fast Cycling",
-		"cost": 35, "max_level": 3, "desc": "Shield returns 1.2s sooner per level.",
-	},
-	{
-		"id": "shd_speed", "vessel": VESSEL_SHIELD, "name": "Thrusters",
-		"cost": 25, "max_level": 3, "desc": "+40 top speed, +60 acceleration per level.",
-	},
-	{
-		"id": "trn_capacity", "vessel": VESSEL_TRANSPORTER, "name": "Expanded Hold",
-		"cost": 30, "max_level": 3, "desc": "Carries 8 more ore per supply run.",
-	},
-	{
-		"id": "trn_speed", "vessel": VESSEL_TRANSPORTER, "name": "Freight Engines",
-		"cost": 30, "max_level": 3, "desc": "+70 speed on supply runs.",
-	},
-]
-
-# Base figures every vessel starts from, before anything is researched.
+# Compatibility constants. VesselDefinition owns the live base figures.
 const SHIP_BASE_DAMAGE: int = 1
 const SHIP_BASE_COOLDOWN: float = 0.5
 const SHIP_BASE_RANGE: float = 320.0
@@ -515,15 +444,13 @@ signal vessel_upgraded(upgrade_id: String)
 
 func has_ship_lab() -> bool:
 	for b in buildings:
-		if b.type == BUILDING_SHIP_LAB:
+		if building_has_capability(b, "vessel_research"):
 			return true
 	return false
 
 
 func shield_vessel_unlocked() -> bool:
-	# Unlocked AT the lab, by paying for it there - a vessel type rather than
-	# a stat, so it is a one-off rather than a level.
-	return int(vessel_levels.get(UNLOCK_SHIELD_VESSEL, 0)) > 0
+	return vessel_is_unlocked(VESSEL_SHIELD)
 
 
 const UNLOCK_SHIELD_VESSEL: String = "unlock_shield"
@@ -531,27 +458,69 @@ const UNLOCK_SHIELD_COST: int = 45
 
 
 func unlock_shield_vessel() -> bool:
-	if shield_vessel_unlocked() or not has_ship_lab():
+	return unlock_vessel(VESSEL_SHIELD)
+
+
+func vessel_definition(vessel: String) -> Resource:
+	return VESSEL_DEFINITIONS.get_definition(vessel)
+
+
+func vessel_name(vessel: String) -> String:
+	var definition: Resource = vessel_definition(vessel)
+	return definition.display_name if definition != null else vessel.capitalize()
+
+
+func vessel_has_capability(vessel: String, capability: String) -> bool:
+	var definition: Resource = vessel_definition(vessel)
+	return definition != null and definition.has_capability(capability)
+
+
+func vessel_is_unlocked(vessel: String) -> bool:
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null:
 		return false
-	if not spend(UNLOCK_SHIELD_COST):
+	return definition.unlock_id == "" or int(vessel_levels.get(definition.unlock_id, 0)) > 0
+
+
+func vessel_for_unlock(unlock_id: String) -> Resource:
+	for definition in VESSEL_DEFINITIONS.all():
+		if definition.unlock_id == unlock_id:
+			return definition
+	return null
+
+
+func unlock_vessel(vessel: String) -> bool:
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null or definition.unlock_id == "" or vessel_is_unlocked(vessel) or not has_ship_lab():
 		return false
-	vessel_levels[UNLOCK_SHIELD_VESSEL] = 1
-	vessel_upgraded.emit(UNLOCK_SHIELD_VESSEL)
+	if not spend(definition.unlock_cost):
+		return false
+	vessel_levels[definition.unlock_id] = 1
+	vessel_upgraded.emit(definition.unlock_id)
 	return true
 
 
 func upgrade_def(id: String) -> Dictionary:
-	for u in VESSEL_UPGRADES:
-		if u.id == id:
-			return u
+	for definition in VESSEL_DEFINITIONS.all():
+		for upgrade in definition.upgrades:
+			if upgrade.upgrade_id == id:
+				return {"id": upgrade.upgrade_id, "vessel": definition.definition_id,
+					"name": upgrade.display_name, "desc": upgrade.description,
+					"cost": upgrade.base_cost, "max_level": upgrade.max_level,
+					"icon": upgrade.icon, "resource": upgrade}
 	return {}
 
 
 func upgrades_for(vessel: String) -> Array:
 	var out: Array = []
-	for u in VESSEL_UPGRADES:
-		if u.vessel == vessel:
-			out.append(u)
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null:
+		return out
+	for upgrade in definition.upgrades:
+		out.append({"id": upgrade.upgrade_id, "vessel": vessel,
+			"name": upgrade.display_name, "desc": upgrade.description,
+			"cost": upgrade.base_cost, "max_level": upgrade.max_level,
+			"icon": upgrade.icon, "resource": upgrade})
 	return out
 
 
@@ -585,77 +554,60 @@ func buy_upgrade(id: String) -> bool:
 	return true
 
 
-# --- what those upgrades actually come to ---------------------------------
-# Read live rather than baked into a vessel when it is built, so researching
-# something improves the ships already flying instead of only the next ones.
-
-func ship_damage(vessel: String) -> int:
-	return SHIP_BASE_DAMAGE + (upgrade_level("int_damage") if vessel == VESSEL_INTERCEPTOR else 0)
+func vessel_stat(vessel: String, stat: String) -> float:
+	var definition: Resource = vessel_definition(vessel)
+	if definition == null:
+		return 0.0
+	var value: float = float(definition.base_stats.get(stat, 0.0))
+	for upgrade in definition.upgrades:
+		var level: int = upgrade_level(upgrade.upgrade_id)
+		value += float(upgrade.additive_modifiers.get(stat, 0.0)) * level
+		if upgrade.multiplicative_modifiers.has(stat):
+			value *= pow(float(upgrade.multiplicative_modifiers[stat]), level)
+	if definition.minimum_stats.has(stat):
+		value = maxf(value, float(definition.minimum_stats[stat]))
+	return value
 
 
-func ship_fire_cooldown(vessel: String) -> float:
-	if vessel != VESSEL_INTERCEPTOR:
-		return SHIP_BASE_COOLDOWN
-	return SHIP_BASE_COOLDOWN * pow(0.85, float(upgrade_level("int_rate")))
-
-
-func ship_fire_range(vessel: String) -> float:
-	return SHIP_BASE_RANGE + (60.0 * upgrade_level("int_range") if vessel == VESSEL_INTERCEPTOR else 0.0)
-
-
-func _speed_levels(vessel: String) -> int:
-	if vessel == VESSEL_SHIELD:
-		return upgrade_level("shd_speed")
-	return upgrade_level("int_speed")
-
-
-func ship_max_speed(vessel: String) -> float:
-	return SHIP_BASE_SPEED + 40.0 * _speed_levels(vessel)
-
-
-func ship_acceleration(vessel: String) -> float:
-	return SHIP_BASE_ACCEL + 60.0 * _speed_levels(vessel)
-
+func ship_damage(vessel: String) -> int: return int(vessel_stat(vessel, "damage"))
+func ship_fire_cooldown(vessel: String) -> float: return vessel_stat(vessel, "fire_cooldown")
+func ship_fire_range(vessel: String) -> float: return vessel_stat(vessel, "fire_range")
+func ship_max_speed(vessel: String) -> float: return vessel_stat(vessel, "max_speed")
+func ship_acceleration(vessel: String) -> float: return vessel_stat(vessel, "acceleration")
 
 func shield_max_charges() -> int:
-	return SHIELD_BASE_CHARGES + upgrade_level("shd_hits")
-
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("shield")
+	return int(vessel_stat(definition.definition_id, "shield_charges"))
 
 func shield_recharge_time() -> float:
-	return maxf(2.0, SHIELD_BASE_RECHARGE - 1.2 * upgrade_level("shd_recharge"))
-
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("shield")
+	return vessel_stat(definition.definition_id, "shield_recharge")
 
 func transporter_load_limit() -> int:
-	return TRANSPORTER_BASE_LOAD + 8 * upgrade_level("trn_capacity")
-
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("transport")
+	return int(vessel_stat(definition.definition_id, "cargo_capacity"))
 
 func transporter_speed() -> float:
-	return TRANSPORTER_BASE_SPEED + 70.0 * upgrade_level("trn_speed")
+	var definition: Resource = VESSEL_DEFINITIONS.with_capability("transport")
+	return vessel_stat(definition.definition_id, "transport_speed")
 
 
 const PRODUCT_SHIP: String = "interceptor"
 const PRODUCT_TRANSPORTER: String = "transporter"
 
-const TRANSPORTER_COST: int = 10
-
 
 func product_cost(product: String) -> int:
-	if product == PRODUCT_TRANSPORTER:
-		return TRANSPORTER_COST
-	if product == VESSEL_SHIELD:
-		return SHIELD_COST
-	return SHIP_COST
+	var definition: Resource = vessel_definition(product)
+	return definition.build_cost if definition != null else 0
 
 
 func can_produce(type: String) -> bool:
-	# Only the ship crafter builds anything. The hub STATIONS transporters,
-	# it does not make them (#12).
-	return type == BUILDING_SHIP_CRAFTER
+	var definition: Resource = BUILDING_DEFINITIONS.get_definition(type)
+	return definition != null and "production" in definition.capabilities
 
 
 func building_stock(id: int) -> int:
-	var b: Dictionary = find_building(id)
-	return 0 if b.is_empty() else int(b.get("stock", 0))
+	return building_resource(id, RESOURCE_ORE)
 
 
 func pending_orders(id: int) -> int:
@@ -702,7 +654,7 @@ func cancel_order(id: int, index: int) -> bool:
 		return false
 	var order: Dictionary = orders[index]
 	if bool(order.started):
-		b.stock = int(b.get("stock", 0)) + product_cost(String(order.product))
+		_inventory_for_record(b).deposit(RESOURCE_ORE, product_cost(String(order.product)))
 	orders.remove_at(index)
 	return true
 
@@ -717,7 +669,7 @@ func outstanding_cost(id: int) -> int:
 		# A started build has already paid, so it is not still owed.
 		if not bool(o.started):
 			need += product_cost(String(o.product))
-	return maxi(need - int(b.get("stock", 0)), 0)
+	return maxi(need - _inventory_for_record(b).amount(RESOURCE_ORE), 0)
 
 
 func deposit_to_building(id: int, amount: int) -> int:
@@ -726,21 +678,21 @@ func deposit_to_building(id: int, amount: int) -> int:
 	var b: Dictionary = find_building(id)
 	if b.is_empty():
 		return 0
-	b.stock = int(b.get("stock", 0)) + amount
-	return amount
+	return _inventory_for_record(b).deposit(RESOURCE_ORE, amount)
 
 
 func queue_order(id: int, product: String = PRODUCT_SHIP) -> bool:
 	var b: Dictionary = find_building(id)
 	if b.is_empty() or not can_produce(b.type):
 		return false
-	if product == VESSEL_SHIELD and not shield_vessel_unlocked():
+	var definition: Resource = vessel_definition(product)
+	if definition == null or not vessel_is_unlocked(product):
 		return false
-	if product == PRODUCT_TRANSPORTER and not has_transport_hub():
+	if definition.has_capability("transport") and not has_transport_hub():
 		# Nowhere to station it. Refused rather than queued, so the player is
 		# told now instead of watching an order sit forever.
 		return false
-	if product == PRODUCT_TRANSPORTER and not can_station_transporter():
+	if definition.has_capability("transport") and not can_station_transporter():
 		# Every berth is taken or spoken for (#20).
 		return false
 	(b.orders as Array).append({"product": product, "elapsed": 0.0, "started": false})
@@ -762,17 +714,19 @@ func _advance_production(delta: float) -> void:
 		var order: Dictionary = orders[0]
 		var product: String = String(order.product)
 		var cost: int = product_cost(product)
+		var inventory: RefCounted = _inventory_for_record(b)
+		var definition: Resource = vessel_definition(product)
 
 		if not bool(order.started):
-			if int(b.get("stock", 0)) < cost:
+			if inventory.amount(RESOURCE_ORE) < cost:
 				continue
-			if product == PRODUCT_TRANSPORTER and transporters.size() >= transport_capacity():
+			if definition.has_capability("transport") and transporters.size() >= transport_capacity():
 				# A hub was demolished after this was ordered, so the berth it
 				# was going to use is gone. Hold rather than overfill.
 				continue
-			if product == PRODUCT_TRANSPORTER and nearest_hub_to(b.position).is_empty():
+			if definition.has_capability("transport") and nearest_hub_to(b.position).is_empty():
 				continue
-			b.stock = int(b.stock) - cost
+			inventory.withdraw(RESOURCE_ORE, cost)
 			order.started = true
 
 		order.elapsed = float(order.elapsed) + delta
@@ -780,7 +734,7 @@ func _advance_production(delta: float) -> void:
 			continue
 
 		orders.pop_front()
-		if product == PRODUCT_TRANSPORTER:
+		if definition.has_capability("transport"):
 			# Transporters are unchanged: they take themselves to the nearest
 			# hub and wait for work (#19).
 			_station_transporter(b.position)
@@ -799,10 +753,11 @@ func _advance_production(delta: float) -> void:
 
 func queue_lab_research(lab_id: int, upgrade_id: String) -> bool:
 	var lab: Dictionary = find_building(lab_id)
-	if lab.is_empty() or lab.type != BUILDING_SHIP_LAB or upgrade_id == "":
+	if not building_has_capability(lab, "vessel_research") or upgrade_id == "":
 		return false
 	var orders: Array = lab.get("research_orders", [])
-	if not orders.is_empty() or (upgrade_id != UNLOCK_SHIELD_VESSEL and upgrade_maxed(upgrade_id)):
+	var unlock_definition: Resource = vessel_for_unlock(upgrade_id)
+	if not orders.is_empty() or (unlock_definition == null and upgrade_maxed(upgrade_id)):
 		return false
 	orders.append({"id": upgrade_id, "elapsed": 0.0, "started": false})
 	lab.research_orders = orders
@@ -817,23 +772,25 @@ func lab_research_order(lab_id: int) -> Dictionary:
 
 func _advance_lab_research(delta: float) -> void:
 	for lab in buildings:
-		if lab.type != BUILDING_SHIP_LAB:
+		if not building_has_capability(lab, "vessel_research"):
 			continue
 		var orders: Array = lab.get("research_orders", [])
 		if orders.is_empty():
 			continue
 		var order: Dictionary = orders[0]
 		var id: String = String(order.id)
-		var cost: int = UNLOCK_SHIELD_COST if id == UNLOCK_SHIELD_VESSEL else upgrade_cost(id)
+		var unlock_definition: Resource = vessel_for_unlock(id)
+		var cost: int = unlock_definition.unlock_cost if unlock_definition != null else upgrade_cost(id)
+		var inventory: RefCounted = _inventory_for_record(lab)
 		if not bool(order.started):
-			if int(lab.get("stock", 0)) < cost:
+			if inventory.amount(RESOURCE_ORE) < cost:
 				continue
-			lab.stock = int(lab.stock) - cost
+			inventory.withdraw(RESOURCE_ORE, cost)
 			order.started = true
 		order.elapsed = float(order.elapsed) + delta
 		if float(order.elapsed) < lab_research_time():
 			continue
-		if id == UNLOCK_SHIELD_VESSEL:
+		if unlock_definition != null:
 			vessel_levels[id] = 1
 		else:
 			vessel_levels[id] = upgrade_level(id) + 1
@@ -862,6 +819,13 @@ func has_mothership() -> bool:
 	return get_mothership_position() != null
 
 
+func has_building_of_type(type: String) -> bool:
+	for building in buildings:
+		if building.type == type:
+			return true
+	return false
+
+
 func remove_buildings_of_type(type: String) -> int:
 	var kept: Array = []
 	var removed: int = 0
@@ -878,7 +842,7 @@ func get_mothership_position() -> Variant:
 	# Where a wiped-out fleet gets rebuilt. Returns null when no mothership
 	# has been built yet, so the caller can fall back to the world origin.
 	for b in buildings:
-		if b.type == BUILDING_MOTHERSHIP:
+		if building_has_capability(b, "bank"):
 			return b.position
 	return null
 
@@ -917,7 +881,7 @@ func rotate_formation(radians: float) -> void:
 # Extractors mine into their OWN local stock. They do not own a magical
 # hauler: ore becomes spendable only when a hub-stationed transporter picks
 # up a full load and physically delivers it to the mothership. Entries are
-# {"position", "planet_name", "resource_type", "stock", "mining_progress"}.
+# {"position", "planet_name", "resource_type", "inventory", "mining_progress"}.
 const EXTRACTOR_RATE: float = 2.0  # ore per second
 
 var extractors: Array = []
@@ -938,7 +902,7 @@ func add_extractor(planet_name: String, at_position: Vector2, resource_type: Str
 		"position": at_position,
 		"planet_name": planet_name,
 		"resource_type": resource_type,
-		"stock": 0,
+		"inventory": INVENTORY.new(),
 		"mining_progress": 0.0,
 	})
 	# An extractor is built from SPACE, with the fleet parked on the planet -
@@ -951,7 +915,21 @@ func add_extractor(planet_name: String, at_position: Vector2, resource_type: Str
 func extractor_stock(index: int) -> int:
 	if index < 0 or index >= extractors.size():
 		return 0
-	return int(extractors[index].get("stock", 0))
+	var extractor: Dictionary = extractors[index]
+	return _extractor_inventory(extractor).amount(String(extractor.get("resource_type", RESOURCE_ORE)))
+
+
+func _extractor_inventory(extractor: Dictionary) -> RefCounted:
+	var inventory: RefCounted = extractor.get("inventory") as RefCounted
+	if inventory == null:
+		inventory = INVENTORY.new()
+		extractor.inventory = inventory
+	# Old extractor state had one stock field whose material was described by
+	# resource_type. Absorb it into that key on first access.
+	if extractor.has("stock"):
+		inventory.set_amount(String(extractor.get("resource_type", RESOURCE_ORE)), int(extractor.stock))
+		extractor.erase("stock")
+	return inventory
 
 
 func _process(delta: float) -> void:
@@ -964,7 +942,7 @@ func _process(delta: float) -> void:
 		e.mining_progress = float(e.get("mining_progress", 0.0)) + delta * EXTRACTOR_RATE
 		var whole: int = int(floor(float(e.mining_progress)))
 		if whole > 0:
-			e.stock = int(e.get("stock", 0)) + whole
+			_extractor_inventory(e).deposit(String(e.get("resource_type", RESOURCE_ORE)), whole)
 			e.mining_progress = float(e.mining_progress) - whole
 	_advance_transporters(delta)
 
@@ -1024,7 +1002,7 @@ func hub_capacity() -> int:
 func hub_count() -> int:
 	var n: int = 0
 	for b in buildings:
-		if b.type == BUILDING_TRANSPORT_HUB:
+		if building_has_capability(b, "transport_hub"):
 			n += 1
 	return n
 
@@ -1039,7 +1017,7 @@ func pending_transporter_orders() -> int:
 	var n: int = 0
 	for b in buildings:
 		for o in b.get("orders", []):
-			if String(o.product) == PRODUCT_TRANSPORTER:
+			if vessel_has_capability(String(o.product), "transport"):
 				n += 1
 	return n
 
@@ -1063,7 +1041,7 @@ func nearest_hub_to(at: Vector2) -> Dictionary:
 	var best: Dictionary = {}
 	var best_d: float = INF
 	for b in buildings:
-		if b.type != BUILDING_TRANSPORT_HUB:
+		if not building_has_capability(b, "transport_hub"):
 			continue
 		var d: float = at.distance_squared_to(b.position)
 		if d < best_d:
@@ -1126,7 +1104,8 @@ func _dispatch_transporters() -> void:
 	var load: int = transporter_load_limit()
 	for i in range(extractors.size()):
 		var extractor: Dictionary = extractors[i]
-		if int(extractor.get("stock", 0)) < load or _transporter_inbound_to_extractor(i):
+		var resource_id: String = String(extractor.get("resource_type", RESOURCE_ORE))
+		if _extractor_inventory(extractor).amount(resource_id) < load or _transporter_inbound_to_extractor(i):
 			continue
 		var chosen_extractor: Dictionary = {}
 		var best_extractor_distance: float = INF
@@ -1140,7 +1119,7 @@ func _dispatch_transporters() -> void:
 		if chosen_extractor.is_empty():
 			return
 		chosen_extractor.extractor_index = i
-		chosen_extractor.resource_type = String(extractor.get("resource_type", "ore"))
+		chosen_extractor.resource_type = resource_id
 		chosen_extractor.target_id = 0
 		_begin_leg(chosen_extractor, transporter_position(chosen_extractor), extractor.position,
 			TRANSPORTER_TO_EXTRACTOR)
@@ -1191,13 +1170,13 @@ func _arrive(t: Dictionary) -> void:
 		TRANSPORTER_TO_MOTHERSHIP:
 			var target: Dictionary = find_building(int(t.target_id))
 			var want: int = outstanding_cost(int(t.target_id))
-			var take: int = mini(mini(want, rocks), transporter_load_limit())
+			var take: int = mini(mini(want, bank_inventory.amount(RESOURCE_ORE)), transporter_load_limit())
 			if take <= 0 or target.is_empty():
 				# Nothing to carry, or the building is gone. Go home empty.
 				t.target_id = 0
 				_begin_leg(t, here, hub_pos if hub_pos != null else here, TRANSPORTER_RETURNING)
 				return
-			rocks -= take
+			bank_inventory.withdraw(RESOURCE_ORE, take)
 			t.carrying = take
 			_begin_leg(t, here, target.position, TRANSPORTER_TO_BUILDING)
 		TRANSPORTER_TO_BUILDING:
@@ -1205,7 +1184,7 @@ func _arrive(t: Dictionary) -> void:
 			if deposit_to_building(int(t.target_id), int(t.carrying)) <= 0:
 				# Building demolished in transit - put the ore back rather
 				# than quietly destroying it.
-				rocks += int(t.carrying)
+				bank_inventory.deposit(RESOURCE_ORE, int(t.carrying))
 			t.carrying = 0
 			t.target_id = 0
 			_begin_leg(t, here, hub_pos if hub_pos != null else here, TRANSPORTER_RETURNING)
@@ -1216,20 +1195,19 @@ func _arrive(t: Dictionary) -> void:
 				return
 			var extractor: Dictionary = extractors[extractor_index]
 			var load: int = transporter_load_limit()
-			if int(extractor.get("stock", 0)) < load:
+			var resource_id: String = String(extractor.get("resource_type", RESOURCE_ORE))
+			var extractor_inventory: RefCounted = _extractor_inventory(extractor)
+			if extractor_inventory.amount(resource_id) < load:
 				t.extractor_index = -1
 				_begin_leg(t, here, hub_pos if hub_pos != null else here, TRANSPORTER_RETURNING)
 				return
-			extractor.stock = int(extractor.stock) - load
+			extractor_inventory.withdraw(resource_id, load)
 			t.carrying = load
-			t.resource_type = String(extractor.get("resource_type", "ore"))
+			t.resource_type = resource_id
 			_begin_leg(t, here, get_mothership_position(), TRANSPORTER_TO_MOTHERSHIP_FROM_EXTRACTOR)
 		TRANSPORTER_TO_MOTHERSHIP_FROM_EXTRACTOR:
 			# Bank only on arrival; cargo retains the extractor's resource type.
-			if String(t.get("resource_type", "ore")) == "gas":
-				gas += int(t.carrying)
-			else:
-				rocks += int(t.carrying)
+			bank_inventory.deposit(String(t.get("resource_type", RESOURCE_ORE)), int(t.carrying))
 			t.carrying = 0
 			t.extractor_index = -1
 			_begin_leg(t, here, hub_pos if hub_pos != null else here, TRANSPORTER_RETURNING)
@@ -1239,11 +1217,11 @@ func _arrive(t: Dictionary) -> void:
 
 
 func can_afford(cost: int) -> bool:
-	return rocks >= cost
+	return bank_inventory.amount(RESOURCE_ORE) >= cost
 
 
 func spend(cost: int) -> bool:
 	if not can_afford(cost):
 		return false
-	rocks -= cost
+	bank_inventory.withdraw(RESOURCE_ORE, cost)
 	return true
diff --git a/GasGiantDefinition.tres b/GasGiantDefinition.tres
new file mode 100644
index 0000000..0a5109c
--- /dev/null
+++ b/GasGiantDefinition.tres
@@ -0,0 +1,14 @@
+[gd_resource type="Resource" script_class="PlanetDefinition" load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://PlanetDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://GasGiantVisual.tscn" id="2"]
+
+[resource]
+script = ExtResource("1")
+definition_id = "gas_giant"
+display_name = "Gas giant"
+names = PackedStringArray("Aurelia", "Boreas", "Cerulean Deep", "Helios Major", "Vesper")
+visual_scene = ExtResource("2")
+surface_profile_id = "gas"
+resource_id = "gas"
+map_color = Color(0.65, 0.42, 0.9, 1)
diff --git a/GasGiantVisual.gd b/GasGiantVisual.gd
new file mode 100644
index 0000000..e9172ca
--- /dev/null
+++ b/GasGiantVisual.gd
@@ -0,0 +1,31 @@
+extends Node2D
+
+var gas_phase: float = 0.0
+
+
+func configure(_shape_seed: int) -> void:
+	queue_redraw()
+
+
+func extractor_anchor() -> Vector2:
+	return Vector2(0.0, -118.0)
+
+
+func _process(delta: float) -> void:
+	gas_phase += delta
+	queue_redraw()
+
+
+func _draw() -> void:
+	var rim := PackedVector2Array()
+	for i in range(32):
+		var angle := TAU * float(i) / 32.0
+		rim.append(Vector2(cos(angle) * 118.0, sin(angle) * 118.0))
+	NeonDraw.draw_glowing_polygon(self, rim, Color(0.4, 0.78, 1.0), 0.9)
+	for row in [-62.0, -28.0, 8.0, 43.0, 73.0]:
+		var band := PackedVector2Array()
+		var half_width: float = sqrt(maxf(0.0, 118.0 * 118.0 - row * row))
+		for i in range(15):
+			var x := lerpf(-half_width, half_width, float(i) / 14.0)
+			band.append(Vector2(x, row + sin(x * 0.045 + gas_phase * 1.6 + row) * 7.0))
+		NeonDraw.draw_glowing_path(self, band, Color(0.85, 0.52, 1.0), 0.75, 0.65)
diff --git a/GasGiantVisual.gd.uid b/GasGiantVisual.gd.uid
new file mode 100644
index 0000000..af718cf
--- /dev/null
+++ b/GasGiantVisual.gd.uid
@@ -0,0 +1 @@
+uid://bxfw4ja2hw4pf
diff --git a/GasGiantVisual.tscn b/GasGiantVisual.tscn
new file mode 100644
index 0000000..513b87e
--- /dev/null
+++ b/GasGiantVisual.tscn
@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://GasGiantVisual.gd" id="1"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
diff --git a/GasResourceDefinition.tres b/GasResourceDefinition.tres
new file mode 100644
index 0000000..a36af07
--- /dev/null
+++ b/GasResourceDefinition.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="ResourceDefinition" load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://ResourceDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://GasResourceGlyph.tscn" id="2"]
+
+[resource]
+script = ExtResource("1")
+resource_id = "gas"
+display_name = "Gas"
+color = Color(0.85, 0.52, 1, 1)
+glyph_scene = ExtResource("2")
diff --git a/GasResourceGlyph.gd b/GasResourceGlyph.gd
new file mode 100644
index 0000000..8bd9965
--- /dev/null
+++ b/GasResourceGlyph.gd
@@ -0,0 +1,19 @@
+extends Control
+
+@export var colour: Color = Color(0.85, 0.52, 1.0)
+
+
+func _draw() -> void:
+	var centre: Vector2 = size * 0.5
+	var radius: float = minf(size.x, size.y) * 0.34
+	var bubbles: Array = [
+		[centre + Vector2(-radius * 0.38, radius * 0.12), radius * 0.46],
+		[centre + Vector2(radius * 0.34, radius * 0.26), radius * 0.58],
+		[centre + Vector2(radius * 0.38, -radius * 0.48), radius * 0.32],
+	]
+	for bubble in bubbles:
+		var ring := PackedVector2Array()
+		for i in range(12):
+			var angle: float = TAU * float(i) / 12.0
+			ring.append(bubble[0] + Vector2(cos(angle), sin(angle)) * float(bubble[1]))
+		NeonDraw.draw_glowing_polygon(self, ring, colour, 1.0, colour.darkened(0.78), maxf(0.5, radius * 0.035))
diff --git a/GasResourceGlyph.gd.uid b/GasResourceGlyph.gd.uid
new file mode 100644
index 0000000..1dfbb0c
--- /dev/null
+++ b/GasResourceGlyph.gd.uid
@@ -0,0 +1 @@
+uid://d1ko6yhtjjavx
diff --git a/GasResourceGlyph.tscn b/GasResourceGlyph.tscn
new file mode 100644
index 0000000..ee02276
--- /dev/null
+++ b/GasResourceGlyph.tscn
@@ -0,0 +1,13 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://GasResourceGlyph.gd" id="1"]
+
+[node name="GlyphVisual" type="Control"]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+mouse_filter = 2
+script = ExtResource("1")
diff --git a/GasSurfaceFeatures.tscn b/GasSurfaceFeatures.tscn
new file mode 100644
index 0000000..576b66d
--- /dev/null
+++ b/GasSurfaceFeatures.tscn
@@ -0,0 +1,7 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://GasVentField.gd" id="1"]
+
+[node name="ResourceProvider" type="Node2D"]
+script = ExtResource("1")
+fleet_path = NodePath("../../Fleet")
diff --git a/GasSurfaceProfile.tres b/GasSurfaceProfile.tres
new file mode 100644
index 0000000..0267c48
--- /dev/null
+++ b/GasSurfaceProfile.tres
@@ -0,0 +1,14 @@
+[gd_resource type="Resource" script_class="PlanetSurfaceProfile" load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://PlanetSurfaceProfile.gd" id="1"]
+[ext_resource type="PackedScene" path="res://GasSurfaceFeatures.tscn" id="2"]
+
+[resource]
+script = ExtResource("1")
+profile_id = "gas"
+features_scene = ExtResource("2")
+base_color = Color(0.13, 0.025, 0.22, 1)
+crater_color = Color(0.055, 0.008, 0.11, 1)
+highlight_color = Color(0.52, 0.17, 0.7, 1)
+caption_color = Color(0.78, 0.88, 0.94, 1)
+caption_outline_color = Color(0.02, 0.01, 0.05, 0.9)
diff --git a/GasVentField.gd b/GasVentField.gd
index 9cdd338..831ca4c 100644
--- a/GasVentField.gd
+++ b/GasVentField.gd
@@ -1,5 +1,6 @@
 extends Node2D
-@onready var fleet: Node2D = get_node("../Fleet")
+@export var fleet_path: NodePath = NodePath("../Fleet")
+@onready var fleet: Node2D = get_node(fleet_path)
 var vents: Array[Vector2] = []
 var progress: float = 0.0
 var emission_phase: float = 0.0
diff --git a/InterceptorDamageUpgrade.tres b/InterceptorDamageUpgrade.tres
new file mode 100644
index 0000000..835851a
--- /dev/null
+++ b/InterceptorDamageUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_damage"
+display_name = "Heavy Slugs"
+description = "+1 damage per shot."
+base_cost = 30
+max_level = 3
+icon = 15
+additive_modifiers = {"damage": 1.0}
diff --git a/InterceptorRangeUpgrade.tres b/InterceptorRangeUpgrade.tres
new file mode 100644
index 0000000..ce01efe
--- /dev/null
+++ b/InterceptorRangeUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_range"
+display_name = "Targeting Array"
+description = "+60 firing range per level."
+base_cost = 20
+max_level = 3
+icon = 17
+additive_modifiers = {"fire_range": 60.0}
diff --git a/InterceptorRateUpgrade.tres b/InterceptorRateUpgrade.tres
new file mode 100644
index 0000000..4add45e
--- /dev/null
+++ b/InterceptorRateUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_rate"
+display_name = "Autoloader"
+description = "Fires 15% faster per level."
+base_cost = 25
+max_level = 3
+icon = 16
+multiplicative_modifiers = {"fire_cooldown": 0.85}
diff --git a/InterceptorSpeedUpgrade.tres b/InterceptorSpeedUpgrade.tres
new file mode 100644
index 0000000..5549971
--- /dev/null
+++ b/InterceptorSpeedUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "int_speed"
+display_name = "Thrusters"
+description = "+40 top speed, +60 acceleration per level."
+base_cost = 25
+max_level = 3
+icon = 18
+additive_modifiers = {"max_speed": 40.0, "acceleration": 60.0}
diff --git a/InterceptorVesselDefinition.tres b/InterceptorVesselDefinition.tres
new file mode 100644
index 0000000..a18f6c4
--- /dev/null
+++ b/InterceptorVesselDefinition.tres
@@ -0,0 +1,20 @@
+[gd_resource type="Resource" script_class="VesselDefinition" load_steps=7 format=3]
+[ext_resource type="Script" path="res://VesselDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://VesselWeaponComponent.tscn" id="2"]
+[ext_resource type="Resource" path="res://InterceptorDamageUpgrade.tres" id="3"]
+[ext_resource type="Resource" path="res://InterceptorRateUpgrade.tres" id="4"]
+[ext_resource type="Resource" path="res://InterceptorRangeUpgrade.tres" id="5"]
+[ext_resource type="Resource" path="res://InterceptorSpeedUpgrade.tres" id="6"]
+[resource]
+script = ExtResource("1")
+definition_id = "interceptor"
+display_name = "Interceptor"
+description = "Fast combat vessel with a rapid-firing cannon."
+build_cost = 6
+build_time = 10.0
+icon = 2
+glow_color = Color(0.25, 0.85, 1, 1)
+capabilities = PackedStringArray("weapon")
+component_scenes = Array[PackedScene]([ExtResource("2")])
+base_stats = {"damage": 1.0, "fire_cooldown": 0.5, "fire_range": 320.0, "max_speed": 460.0, "acceleration": 450.0}
+upgrades = Array[Resource]([ExtResource("3"), ExtResource("4"), ExtResource("5"), ExtResource("6")])
diff --git a/Inventory.gd b/Inventory.gd
new file mode 100644
index 0000000..aab25fd
--- /dev/null
+++ b/Inventory.gd
@@ -0,0 +1,79 @@
+class_name Inventory
+extends RefCounted
+
+var total_capacity: int = -1
+var resource_capacities: Dictionary = {}
+var _amounts: Dictionary = {}
+
+
+func _init(initial: Dictionary = {}, capacity: int = -1) -> void:
+	total_capacity = capacity
+	for resource_id in initial:
+		set_amount(String(resource_id), int(initial[resource_id]))
+
+
+func amount(resource_id: String) -> int:
+	return int(_amounts.get(resource_id, 0))
+
+
+func total() -> int:
+	var result: int = 0
+	for value in _amounts.values():
+		result += int(value)
+	return result
+
+
+func capacity_for(resource_id: String) -> int:
+	return int(resource_capacities.get(resource_id, -1))
+
+
+func space_for(resource_id: String) -> int:
+	var space: int = 1 << 30
+	if total_capacity >= 0:
+		space = maxi(total_capacity - total(), 0)
+	var resource_capacity: int = capacity_for(resource_id)
+	if resource_capacity >= 0:
+		space = mini(space, maxi(resource_capacity - amount(resource_id), 0))
+	return space
+
+
+func set_amount(resource_id: String, value: int) -> int:
+	_amounts.erase(resource_id)
+	var accepted: int = mini(maxi(value, 0), space_for(resource_id))
+	if accepted > 0:
+		_amounts[resource_id] = accepted
+	return amount(resource_id)
+
+
+func deposit(resource_id: String, requested: int) -> int:
+	var moved: int = mini(maxi(requested, 0), space_for(resource_id))
+	if moved > 0:
+		_amounts[resource_id] = amount(resource_id) + moved
+	return moved
+
+
+func withdraw(resource_id: String, requested: int) -> int:
+	var moved: int = mini(maxi(requested, 0), amount(resource_id))
+	if moved <= 0:
+		return 0
+	var remaining: int = amount(resource_id) - moved
+	if remaining > 0:
+		_amounts[resource_id] = remaining
+	else:
+		_amounts.erase(resource_id)
+	return moved
+
+
+func transfer_to(destination: Inventory, resource_id: String, requested: int) -> int:
+	if destination == null:
+		return 0
+	var moved: int = mini(mini(maxi(requested, 0), amount(resource_id)), destination.space_for(resource_id))
+	if moved <= 0:
+		return 0
+	withdraw(resource_id, moved)
+	destination.deposit(resource_id, moved)
+	return moved
+
+
+func snapshot() -> Dictionary:
+	return _amounts.duplicate()
diff --git a/Inventory.gd.uid b/Inventory.gd.uid
new file mode 100644
index 0000000..59722a2
--- /dev/null
+++ b/Inventory.gd.uid
@@ -0,0 +1 @@
+uid://celx1yj6cp2rf
diff --git a/MothershipBuildingDefinition.tres b/MothershipBuildingDefinition.tres
new file mode 100644
index 0000000..a032777
--- /dev/null
+++ b/MothershipBuildingDefinition.tres
@@ -0,0 +1,21 @@
+[gd_resource type="Resource" script_class="BuildingDefinition" load_steps=3 format=3]
+[ext_resource type="Script" path="res://BuildingDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://MothershipBuildingVisual.tscn" id="2"]
+[resource]
+script = ExtResource("1")
+definition_id = "mothership"
+display_name = "Mothership"
+description = "Fleet home port. A wiped-out fleet rebuilds here, and extractor transports deliver resources here."
+cost = 20
+action_icon = 8
+menu_icon = 8
+visual_scene = ExtResource("2")
+capabilities = PackedStringArray("bank", "research", "hangar")
+map_color = Color(0.45, 0.9, 0.55, 1)
+map_sides = 6
+map_radius = 8.0
+map_phase = 0.523599
+menu_button_name = "MothershipButton"
+menu_label_name = "MothershipLabel"
+menu_cost_name = "MothershipCost"
+unique = true
diff --git a/MothershipBuildingVisual.gd b/MothershipBuildingVisual.gd
new file mode 100644
index 0000000..ba2f617
--- /dev/null
+++ b/MothershipBuildingVisual.gd
@@ -0,0 +1,12 @@
+extends "res://BuildingVisualBase.gd"
+
+func _ready() -> void:
+	_build_mothership_pieces()
+	queue_redraw()
+
+func apply_animation() -> void:
+	_animate_mothership()
+
+func _draw() -> void:
+	register_draw()
+	_draw_mothership_static(self)
diff --git a/MothershipBuildingVisual.gd.uid b/MothershipBuildingVisual.gd.uid
new file mode 100644
index 0000000..7ac3669
--- /dev/null
+++ b/MothershipBuildingVisual.gd.uid
@@ -0,0 +1 @@
+uid://m43bwdwhqgy4
diff --git a/MothershipBuildingVisual.tscn b/MothershipBuildingVisual.tscn
new file mode 100644
index 0000000..0cc3615
--- /dev/null
+++ b/MothershipBuildingVisual.tscn
@@ -0,0 +1,11 @@
+[gd_scene load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://MothershipBuildingVisual.gd" id="1"]
+[ext_resource type="Script" path="res://BuildingActionProvider.gd" id="2"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
+
+[node name="ActionProvider" type="Node" parent="."]
+script = ExtResource("2")
+actions = PackedStringArray("research", "transfer", "hangar")
diff --git a/OreResourceDefinition.tres b/OreResourceDefinition.tres
new file mode 100644
index 0000000..6da27dc
--- /dev/null
+++ b/OreResourceDefinition.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="ResourceDefinition" load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://ResourceDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://OreResourceGlyph.tscn" id="2"]
+
+[resource]
+script = ExtResource("1")
+resource_id = "ore"
+display_name = "Ore"
+color = Color(0, 0.72, 0.82, 1)
+glyph_scene = ExtResource("2")
diff --git a/OreResourceGlyph.gd b/OreResourceGlyph.gd
new file mode 100644
index 0000000..e28f7a3
--- /dev/null
+++ b/OreResourceGlyph.gd
@@ -0,0 +1,14 @@
+extends Control
+
+@export var colour: Color = Color(0.0, 0.72, 0.82)
+
+
+func _draw() -> void:
+	var centre: Vector2 = size * 0.5
+	var radius: float = minf(size.x, size.y) * 0.34
+	var points := PackedVector2Array()
+	for i in range(6):
+		var angle: float = TAU * float(i) / 6.0 - PI * 0.5
+		points.append(centre + Vector2(cos(angle), sin(angle)) * radius)
+	NeonDraw.draw_glowing_polygon(self, points, colour, 1.0, colour.darkened(0.78), maxf(0.5, radius * 0.035))
+	NeonDraw.draw_glowing_line(self, points[5], points[2], colour, 0.55, maxf(0.4, radius * 0.025), colour.darkened(0.78))
diff --git a/OreResourceGlyph.gd.uid b/OreResourceGlyph.gd.uid
new file mode 100644
index 0000000..2ba6598
--- /dev/null
+++ b/OreResourceGlyph.gd.uid
@@ -0,0 +1 @@
+uid://cwgkhqo4ev5ao
diff --git a/OreResourceGlyph.tscn b/OreResourceGlyph.tscn
new file mode 100644
index 0000000..384a20e
--- /dev/null
+++ b/OreResourceGlyph.tscn
@@ -0,0 +1,13 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://OreResourceGlyph.gd" id="1"]
+
+[node name="GlyphVisual" type="Control"]
+layout_mode = 3
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+mouse_filter = 2
+script = ExtResource("1")
diff --git a/Planet.gd b/Planet.gd
index c4eddbd..4d17d84 100644
--- a/Planet.gd
+++ b/Planet.gd
@@ -1,5 +1,8 @@
 extends Node2D
 
+const PLANET_DEFINITIONS = preload("res://PlanetDefinitions.gd")
+
+
 # A landable world-object - unlike regular Asteroid.gd, planets are
 # stationary ("Big Stable Asteroid" - stable means it doesn't drift or
 # destroy ships on touch). Whether the fleet counts as "landed" is decided
@@ -11,15 +14,33 @@ extends Node2D
 # while the fleet as a whole was clearly sitting on the planet.
 
 @export var planet_name: String = ""
-@export var planet_type: String = "rocky"
-@export var resource_type: String = "ore"
+@export var definition_id: String = PLANET_DEFINITIONS.DEFAULT_DEFINITION_ID
 @export var landing_radius: float = 140.0
 # Set by whoever spawns this planet (PlanetField, seeded from the chunk's
 # own coordinates) so the outline shape is stable across respawns of the
 # same chunk, instead of reading as a "different" planet every time.
 @export var shape_seed: int = 0
 
-var shape_points: PackedVector2Array = PackedVector2Array()
+var definition: Resource
+var visual: Node2D
+
+var resource_type: String:
+	get: return String(definition.resource_id) if definition != null else "ore"
+
+var surface_profile_id: String:
+	get: return String(definition.surface_profile_id) if definition != null else "rocky"
+
+var shape_points: PackedVector2Array:
+	get:
+		if visual != null and "shape_points" in visual:
+			return visual.shape_points
+		return PackedVector2Array()
+
+var gas_phase: float:
+	get:
+		if visual != null and "gas_phase" in visual:
+			return float(visual.gas_phase)
+		return 0.0
 
 # An extractor is built down on this planet's SURFACE, in a different scene
 # the player is no longer looking at, so from space nothing distinguished a
@@ -37,31 +58,20 @@ const DERRICK_HALF_WIDTH: float = 16.0
 # only at _ready() left the planet looking untouched until it happened to
 # despawn and respawn.
 var shows_extractor: bool = false
-var gas_phase: float = 0.0
 
 
 func _ready() -> void:
 	add_to_group("planets")
 	z_index = -1
-
-	var rng: RandomNumberGenerator = RandomNumberGenerator.new()
-	rng.seed = shape_seed
-	var point_count: int = 10
-	for i in range(point_count):
-		var angle: float = (float(i) / point_count) * TAU
-		var radius: float = rng.randf_range(70.0, 100.0)
-		shape_points.append(Vector2(cos(angle), sin(angle)) * radius)
+	definition = PLANET_DEFINITIONS.get_definition(definition_id)
+	visual = definition.visual_scene.instantiate()
+	visual.configure(shape_seed)
+	get_node("VisualHost").add_child(visual)
 	shows_extractor = GameState.has_extractor_at(planet_name)
 	GameState.extractor_added.connect(_on_extractor_added)
 	queue_redraw()
 
 
-func _process(delta: float) -> void:
-	if planet_type == "gas_giant":
-		gas_phase += delta
-		queue_redraw()
-
-
 func _on_extractor_added(built_on: String) -> void:
 	# Only the planet it was actually built on, and only a redraw when the
 	# answer really changed - every other planet in range gets this too.
@@ -72,14 +82,9 @@ func _on_extractor_added(built_on: String) -> void:
 
 
 func extractor_derrick_anchor() -> Vector2:
-	# The rim vertex the derrick stands on: the shape's own topmost point,
-	# rather than a fixed radius, so it sits ON the outline whatever lumpy
-	# shape the seed drew instead of floating off it or sinking inside it.
-	var base: Vector2 = Vector2(0.0, -100.0)
-	for p in shape_points:
-		if p.y < base.y:
-			base = p
-	return base
+	if visual != null and visual.has_method("extractor_anchor"):
+		return visual.extractor_anchor()
+	return Vector2(0.0, -100.0)
 
 
 func extractor_derrick_tip() -> Vector2:
@@ -111,28 +116,5 @@ func extractor_derrick_points() -> PackedVector2Array:
 
 
 func _draw() -> void:
-	if planet_type == "gas_giant":
-		_draw_gas_giant()
-		if shows_extractor:
-			NeonDraw.draw_glowing_polygon(self, extractor_derrick_points(), EXTRACTOR_MARKER_COLOR, 1.0)
-		return
-	NeonDraw.draw_glowing_polygon(self, shape_points, Color(0.6, 0.55, 0.5), 1.0)
 	if shows_extractor:
 		NeonDraw.draw_glowing_polygon(self, extractor_derrick_points(), EXTRACTOR_MARKER_COLOR, 1.0)
-
-
-func _draw_gas_giant() -> void:
-	# A round, animated giant with drifting latitudinal bands. It is visibly
-	# unlike the rocky outline and keeps moving even while the fleet is idle.
-	var rim := PackedVector2Array()
-	for i in range(32):
-		var a := TAU * float(i) / 32.0
-		rim.append(Vector2(cos(a) * 118.0, sin(a) * 118.0))
-	NeonDraw.draw_glowing_polygon(self, rim, Color(0.4, 0.78, 1.0), 0.9)
-	for row in [-62.0, -28.0, 8.0, 43.0, 73.0]:
-		var band := PackedVector2Array()
-		var half_width: float = sqrt(maxf(0.0, 118.0 * 118.0 - row * row))
-		for i in range(15):
-			var x := lerpf(-half_width, half_width, float(i) / 14.0)
-			band.append(Vector2(x, row + sin(x * 0.045 + gas_phase * 1.6 + row) * 7.0))
-		NeonDraw.draw_glowing_path(self, band, Color(0.85, 0.52, 1.0), 0.75, 0.65)
diff --git a/Planet.tscn b/Planet.tscn
index 844672b..0e7fe1f 100644
--- a/Planet.tscn
+++ b/Planet.tscn
@@ -4,3 +4,5 @@
 
 [node name="Planet" type="Node2D"]
 script = ExtResource("1")
+
+[node name="VisualHost" type="Node2D" parent="."]
diff --git a/PlanetAtmosphereController.gd b/PlanetAtmosphereController.gd
index cc497d4..3a66ea4 100644
--- a/PlanetAtmosphereController.gd
+++ b/PlanetAtmosphereController.gd
@@ -113,7 +113,7 @@ func _on_enter_pressed() -> void:
 	GameState.return_world_position = current_planet.position
 	GameState.return_camera_zoom = camera.zoom.x
 	GameState.planet_name = current_planet.planet_name
-	GameState.planet_type = current_planet.planet_type
+	GameState.planet_definition_id = current_planet.definition_id
 
 	var tween: Tween = create_tween()
 	tween.tween_property(fade_rect, "color:a", 1.0, fade_duration)
diff --git a/PlanetDefinition.gd b/PlanetDefinition.gd
new file mode 100644
index 0000000..e184241
--- /dev/null
+++ b/PlanetDefinition.gd
@@ -0,0 +1,10 @@
+class_name PlanetDefinition
+extends Resource
+
+@export var definition_id: String = "rocky"
+@export var display_name: String = "Rocky planet"
+@export var names: PackedStringArray = []
+@export var visual_scene: PackedScene
+@export var surface_profile_id: String = "rocky"
+@export var resource_id: String = "ore"
+@export var map_color: Color = Color(0.7, 0.65, 0.55)
diff --git a/PlanetDefinition.gd.uid b/PlanetDefinition.gd.uid
new file mode 100644
index 0000000..ee09e6d
--- /dev/null
+++ b/PlanetDefinition.gd.uid
@@ -0,0 +1 @@
+uid://dt6tsdmmlnfaf
diff --git a/PlanetDefinitions.gd b/PlanetDefinitions.gd
new file mode 100644
index 0000000..fa9dd2d
--- /dev/null
+++ b/PlanetDefinitions.gd
@@ -0,0 +1,14 @@
+class_name PlanetDefinitions
+extends RefCounted
+
+const ROCKY_ID: String = "rocky"
+const GAS_GIANT_ID: String = "gas_giant"
+const DEFAULT_DEFINITION_ID: String = ROCKY_ID
+const DEFINITIONS: Dictionary = {
+	ROCKY_ID: preload("res://RockyPlanetDefinition.tres"),
+	GAS_GIANT_ID: preload("res://GasGiantDefinition.tres"),
+}
+
+
+static func get_definition(definition_id: String) -> Resource:
+	return DEFINITIONS.get(definition_id, DEFINITIONS[DEFAULT_DEFINITION_ID])
diff --git a/PlanetDefinitions.gd.uid b/PlanetDefinitions.gd.uid
new file mode 100644
index 0000000..188741c
--- /dev/null
+++ b/PlanetDefinitions.gd.uid
@@ -0,0 +1 @@
+uid://ipsld2ex2t8e
diff --git a/PlanetField.gd b/PlanetField.gd
index 4dbbdd8..6a8c3c6 100644
--- a/PlanetField.gd
+++ b/PlanetField.gd
@@ -1,5 +1,6 @@
 extends Node2D
 
+
 # Spawns "Big Stable Asteroid" planets in ASTEROID_FIELD biome chunks near
 # the fleet where WorldGen says one belongs, and despawns them once the
 # fleet has moved far enough away - mirrors AsteroidField's chunk-lifecycle
@@ -83,8 +84,7 @@ func _spawn_chunk_planet(chunk: Vector2i) -> void:
 	planet.position = origin + data.local_pos
 	planet.planet_name = data.name
 	planet.shape_seed = data.shape_seed
-	planet.planet_type = String(data.get("planet_type", "rocky"))
-	planet.resource_type = String(data.get("resource_type", "ore"))
+	planet.definition_id = String(data.get("definition_id", "rocky"))
 	# Deferred: update_chunks() can run synchronously from inside a
 	# parent's own _ready() chain (forced once right after the fleet is
 	# positioned, to avoid a pop-in on scene load) - Godot refuses a
diff --git a/PlanetSurface.tscn b/PlanetSurface.tscn
index 507ec2b..81cea2d 100644
--- a/PlanetSurface.tscn
+++ b/PlanetSurface.tscn
@@ -7,9 +7,7 @@
 [ext_resource type="Script" path="res://PlanetSurfaceController.gd" id="5"]
 [ext_resource type="Script" path="res://IconButton.gd" id="6"]
 [ext_resource type="Script" path="res://TouchJoystick.gd" id="7"]
-[ext_resource type="Script" path="res://RockField.gd" id="8"]
 [ext_resource type="Script" path="res://ResourceCounter.gd" id="9"]
-[ext_resource type="Script" path="res://GasVentField.gd" id="10"]
 [ext_resource type="Script" path="res://GasCounter.gd" id="11"]
 [ext_resource type="Script" path="res://CargoCounter.gd" id="12"]
 [ext_resource type="Script" path="res://GasCargoCounter.gd" id="13"]
@@ -49,12 +47,7 @@ ship_core_color = Color(0.02, 0.09, 0.15, 1)
 position = Vector2(0, 0)
 zoom = Vector2(1, 1)
 
-[node name="RockField" type="Node2D" parent="."]
-script = ExtResource("8")
-
-[node name="GasVentField" type="Node2D" parent="."]
-visible = false
-script = ExtResource("10")
+[node name="SurfaceFeatures" type="Node2D" parent="."]
 
 [node name="SurfaceController" type="Node2D" parent="."]
 script = ExtResource("5")
diff --git a/PlanetSurfaceController.gd b/PlanetSurfaceController.gd
index 502d8d4..7c683d4 100644
--- a/PlanetSurfaceController.gd
+++ b/PlanetSurfaceController.gd
@@ -1,5 +1,8 @@
 extends Node2D
 
+const SURFACE_PROFILES = preload("res://PlanetSurfaceProfiles.gd")
+const PLANET_DEFINITIONS = preload("res://PlanetDefinitions.gd")
+
 # Bootstraps the surviving fleet on this scene's own startup (from
 # GameState, since this is a fresh scene tree - nothing here carries
 # over automatically) and handles the always-available exit prompt that
@@ -13,29 +16,15 @@ extends Node2D
 @onready var planet_name_label: Label = get_node("../UI/PlanetNameLabel")
 @onready var exit_button: IconButton = get_node("../UI/ExitButton")
 @onready var fade_rect: ColorRect = get_node("../FadeOverlay/FadeRect")
+@onready var background: ColorRect = get_node("../BackgroundLayer/LunarBackground")
+@onready var feature_host: Node2D = get_node("../SurfaceFeatures")
 
 var transitioning: bool = false
 
 
 func _ready() -> void:
-	if GameState.planet_type == "gas_giant":
-		# A gas giant is not lunar terrain: its surface view uses a deep,
-		# coloured atmosphere instead of the rocky field. The background is
-		# shader-driven, so changing ColorRect.color does not tint it; update
-		# the actual palette uniforms.
-		get_node("../RockField").visible = false
-		get_node("../GasVentField").visible = true
-		var background: ColorRect = get_node("../BackgroundLayer/LunarBackground")
-		var atmosphere: ShaderMaterial = background.material
-		atmosphere.set_shader_parameter("base_color", Color(0.13, 0.025, 0.22, 1.0))
-		atmosphere.set_shader_parameter("crater_color", Color(0.055, 0.008, 0.11, 1.0))
-		atmosphere.set_shader_parameter("highlight_color", Color(0.52, 0.17, 0.7, 1.0))
-		# The lunar surface uses dark captions on a bright ground. Flip only
-		# those captions for the night-dark gas atmosphere.
-		for caption_path in ["../UI/BankCaption", "../UI/FleetCaption"]:
-			var caption: Label = get_node(caption_path)
-			caption.add_theme_color_override("font_color", Color(0.78, 0.88, 0.94))
-			caption.add_theme_color_override("font_outline_color", Color(0.02, 0.01, 0.05, 0.9))
+	var planet_definition: Resource = PLANET_DEFINITIONS.get_definition(GameState.planet_definition_id)
+	_compose_surface(SURFACE_PROFILES.get_profile(planet_definition.surface_profile_id))
 	fleet.spawn_ships(GameState.surviving_ship_count, Vector2.ZERO)
 	camera.position = Vector2.ZERO
 	camera.zoom = Vector2(GameState.return_camera_zoom, GameState.return_camera_zoom)
@@ -47,6 +36,21 @@ func _ready() -> void:
 	tween.tween_property(fade_rect, "color:a", 0.0, fade_duration)
 
 
+func _compose_surface(profile: Resource) -> void:
+	var atmosphere: ShaderMaterial = background.material
+	atmosphere.set_shader_parameter("base_color", profile.base_color)
+	atmosphere.set_shader_parameter("crater_color", profile.crater_color)
+	atmosphere.set_shader_parameter("highlight_color", profile.highlight_color)
+	for caption_path in ["../UI/BankCaption", "../UI/FleetCaption"]:
+		var caption: Label = get_node(caption_path)
+		caption.add_theme_color_override("font_color", profile.caption_color)
+		caption.add_theme_color_override("font_outline_color", profile.caption_outline_color)
+	if profile.features_scene == null:
+		return
+	var features: Node = profile.features_scene.instantiate()
+	feature_host.add_child(features)
+
+
 func _on_exit_pressed() -> void:
 	if transitioning:
 		return
diff --git a/PlanetSurfaceProfile.gd b/PlanetSurfaceProfile.gd
new file mode 100644
index 0000000..d2ea9be
--- /dev/null
+++ b/PlanetSurfaceProfile.gd
@@ -0,0 +1,13 @@
+class_name PlanetSurfaceProfile
+extends Resource
+
+# Declarative recipe for a landed planet surface. The host scene only knows
+# how to apply one of these; the feature scene owns the actual resource nodes.
+
+@export var profile_id: String = "rocky"
+@export var features_scene: PackedScene
+@export var base_color: Color = Color(0.75, 0.75, 0.76, 1.0)
+@export var crater_color: Color = Color(0.44, 0.44, 0.45, 1.0)
+@export var highlight_color: Color = Color(0.89, 0.89, 0.9, 1.0)
+@export var caption_color: Color = Color(0.08, 0.16, 0.2, 1.0)
+@export var caption_outline_color: Color = Color(0.9, 0.95, 0.96, 0.8)
diff --git a/PlanetSurfaceProfile.gd.uid b/PlanetSurfaceProfile.gd.uid
new file mode 100644
index 0000000..884fe16
--- /dev/null
+++ b/PlanetSurfaceProfile.gd.uid
@@ -0,0 +1 @@
+uid://b31vef6ge1tjh
diff --git a/PlanetSurfaceProfiles.gd b/PlanetSurfaceProfiles.gd
new file mode 100644
index 0000000..97da418
--- /dev/null
+++ b/PlanetSurfaceProfiles.gd
@@ -0,0 +1,12 @@
+class_name PlanetSurfaceProfiles
+extends RefCounted
+
+const DEFAULT_PROFILE_ID: String = "rocky"
+const PROFILES: Dictionary = {
+	"rocky": preload("res://RockySurfaceProfile.tres"),
+	"gas": preload("res://GasSurfaceProfile.tres"),
+}
+
+
+static func get_profile(profile_id: String) -> Resource:
+	return PROFILES.get(profile_id, PROFILES[DEFAULT_PROFILE_ID])
diff --git a/PlanetSurfaceProfiles.gd.uid b/PlanetSurfaceProfiles.gd.uid
new file mode 100644
index 0000000..c0f3f93
--- /dev/null
+++ b/PlanetSurfaceProfiles.gd.uid
@@ -0,0 +1 @@
+uid://bufr6mnwbobxb
diff --git a/ResourceBar.gd b/ResourceBar.gd
index 2bf11b4..6594fc1 100644
--- a/ResourceBar.gd
+++ b/ResourceBar.gd
@@ -3,7 +3,7 @@ extends Control
 
 # Compact resource table shared by crafting, research and the ship lab.
 # Rows are resources; columns are locations. Adding another material to
-# GameState.RESOURCE_TYPES automatically gives it a row here.
+# The resource-definition catalog automatically gives each material a row.
 
 var building_id: int = 0
 
@@ -24,7 +24,7 @@ func _ready() -> void:
 		add_child(label)
 		_header_labels.append(label)
 
-	for resource_type in GameState.RESOURCE_TYPES:
+	for resource_type in GameState.resource_types():
 		var glyph := ResourceGlyph.new()
 		glyph.resource_type = resource_type
 		add_child(glyph)
@@ -78,7 +78,7 @@ func _layout() -> void:
 
 	var row_height: float = (size.y - HEADER_HEIGHT - 4.0) / maxf(1.0, float(_rows.size()))
 	var row_index: int = 0
-	for resource_type in GameState.RESOURCE_TYPES:
+	for resource_type in GameState.resource_types():
 		var row: Dictionary = _rows[resource_type]
 		var y: float = HEADER_HEIGHT + float(row_index) * row_height
 		row.glyph.position = Vector2(2.0, y + 2.0)
@@ -94,7 +94,7 @@ func _layout() -> void:
 
 
 func _process(_delta: float) -> void:
-	for resource_type in GameState.RESOURCE_TYPES:
+	for resource_type in GameState.resource_types():
 		var row: Dictionary = _rows.get(resource_type, {})
 		if row.is_empty():
 			continue
diff --git a/ResourceDefinition.gd b/ResourceDefinition.gd
new file mode 100644
index 0000000..acb5acc
--- /dev/null
+++ b/ResourceDefinition.gd
@@ -0,0 +1,7 @@
+class_name ResourceDefinition
+extends Resource
+
+@export var resource_id: String = "ore"
+@export var display_name: String = "Ore"
+@export var color: Color = Color.WHITE
+@export var glyph_scene: PackedScene
diff --git a/ResourceDefinition.gd.uid b/ResourceDefinition.gd.uid
new file mode 100644
index 0000000..440e5e4
--- /dev/null
+++ b/ResourceDefinition.gd.uid
@@ -0,0 +1 @@
+uid://kvy02iu7pbyu
diff --git a/ResourceDefinitions.gd b/ResourceDefinitions.gd
new file mode 100644
index 0000000..7ddf4c0
--- /dev/null
+++ b/ResourceDefinitions.gd
@@ -0,0 +1,18 @@
+class_name ResourceDefinitions
+extends RefCounted
+
+const ORE_ID: String = "ore"
+const GAS_ID: String = "gas"
+const ORDER: PackedStringArray = [ORE_ID, GAS_ID]
+const DEFINITIONS: Dictionary = {
+	ORE_ID: preload("res://OreResourceDefinition.tres"),
+	GAS_ID: preload("res://GasResourceDefinition.tres"),
+}
+
+
+static func get_definition(resource_id: String) -> Resource:
+	return DEFINITIONS.get(resource_id)
+
+
+static func ids() -> PackedStringArray:
+	return ORDER
diff --git a/ResourceDefinitions.gd.uid b/ResourceDefinitions.gd.uid
new file mode 100644
index 0000000..9ef7d79
--- /dev/null
+++ b/ResourceDefinitions.gd.uid
@@ -0,0 +1 @@
+uid://ci7yyyxyd3o67
diff --git a/ResourceGlyph.gd b/ResourceGlyph.gd
index aa80578..14a90d0 100644
--- a/ResourceGlyph.gd
+++ b/ResourceGlyph.gd
@@ -1,6 +1,8 @@
 class_name ResourceGlyph
 extends Control
 
+const RESOURCE_DEFINITIONS = preload("res://ResourceDefinitions.gd")
+
 # A small, non-interactive resource mark shared by tables and transfer rows.
 # Resource buttons used to borrow IconButton, which made decorative icons
 # look tappable and encouraged each screen to invent its own version.
@@ -12,43 +14,21 @@ func set_resource_type(value: String) -> void:
 	if resource_type == value:
 		return
 	resource_type = value
-	queue_redraw()
+	if is_node_ready():
+		_rebuild_visual()
 
 
 func _ready() -> void:
 	mouse_filter = Control.MOUSE_FILTER_IGNORE
-	queue_redraw()
+	_rebuild_visual()
 
 
-func _draw() -> void:
-	var colour: Color = GameState.resource_color(resource_type)
-	var centre: Vector2 = size * 0.5
-	var radius: float = minf(size.x, size.y) * 0.34
-	match resource_type:
-		GameState.RESOURCE_GAS:
-			_draw_gas(centre, radius, colour)
-		_:
-			_draw_ore(centre, radius, colour)
-
-
-func _draw_ore(centre: Vector2, radius: float, colour: Color) -> void:
-	var points := PackedVector2Array()
-	for i in range(6):
-		var angle: float = TAU * float(i) / 6.0 - PI * 0.5
-		points.append(centre + Vector2(cos(angle), sin(angle)) * radius)
-	NeonDraw.draw_glowing_polygon(self, points, colour, 1.0, colour.darkened(0.78), maxf(0.5, radius * 0.035))
-	NeonDraw.draw_glowing_line(self, points[5], points[2], colour, 0.55, maxf(0.4, radius * 0.025), colour.darkened(0.78))
-
-
-func _draw_gas(centre: Vector2, radius: float, colour: Color) -> void:
-	var bubbles: Array = [
-		[centre + Vector2(-radius * 0.38, radius * 0.12), radius * 0.46],
-		[centre + Vector2(radius * 0.34, radius * 0.26), radius * 0.58],
-		[centre + Vector2(radius * 0.38, -radius * 0.48), radius * 0.32],
-	]
-	for bubble in bubbles:
-		var ring := PackedVector2Array()
-		for i in range(12):
-			var angle: float = TAU * float(i) / 12.0
-			ring.append(bubble[0] + Vector2(cos(angle), sin(angle)) * float(bubble[1]))
-		NeonDraw.draw_glowing_polygon(self, ring, colour, 1.0, colour.darkened(0.78), maxf(0.5, radius * 0.035))
+func _rebuild_visual() -> void:
+	for child in get_children():
+		child.queue_free()
+	var definition: Resource = RESOURCE_DEFINITIONS.get_definition(resource_type)
+	if definition == null or definition.glyph_scene == null:
+		return
+	var visual: Control = definition.glyph_scene.instantiate()
+	visual.colour = definition.color
+	add_child(visual)
diff --git a/ResourceTransferList.gd b/ResourceTransferList.gd
index 1883119..859f0f1 100644
--- a/ResourceTransferList.gd
+++ b/ResourceTransferList.gd
@@ -27,7 +27,7 @@ func _ready() -> void:
 	_destination_heading.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
 	add_child(_destination_heading)
 
-	for resource_type in GameState.RESOURCE_TYPES:
+	for resource_type in GameState.resource_types():
 		var colour: Color = GameState.resource_color(resource_type)
 		var glyph := ResourceGlyph.new()
 		glyph.resource_type = resource_type
@@ -140,7 +140,7 @@ func set_destination(id: int, heading: String) -> void:
 
 
 func refresh() -> void:
-	for resource_type in GameState.RESOURCE_TYPES:
+	for resource_type in GameState.resource_types():
 		var row: Dictionary = _rows.get(resource_type, {})
 		if row.is_empty():
 			continue
@@ -169,7 +169,7 @@ func _layout() -> void:
 
 	var row_height: float = (size.y - HEADER_HEIGHT) / maxf(1.0, float(_rows.size()))
 	var row_index: int = 0
-	for resource_type in GameState.RESOURCE_TYPES:
+	for resource_type in GameState.resource_types():
 		var row: Dictionary = _rows[resource_type]
 		var y: float = HEADER_HEIGHT + float(row_index) * row_height
 		var glyph_size: float = minf(66.0, row_height * 0.23)
diff --git a/RockField.gd b/RockField.gd
index a82389c..dd839ed 100644
--- a/RockField.gd
+++ b/RockField.gd
@@ -17,7 +17,8 @@ extends Node2D
 @export var despawn_radius: float = 2600.0
 @export var check_interval: float = 0.5
 
-@onready var fleet: Node2D = get_node("../Fleet")
+@export var fleet_path: NodePath = NodePath("../Fleet")
+@onready var fleet: Node2D = get_node(fleet_path)
 
 var rock_scene: PackedScene = preload("res://Rock.tscn")
 var rocks: Array = []
@@ -26,12 +27,6 @@ var rng: RandomNumberGenerator = RandomNumberGenerator.new()
 
 
 func _ready() -> void:
-	# Gas giants have their own gas vents and must never receive ore pickups.
-	# This check happens before the initial population pass, unlike merely
-	# hiding the field later from PlanetSurfaceController.
-	if GameState.planet_type == "gas_giant":
-		set_process(false)
-		return
 	rng.randomize()
 	# Populate immediately rather than waiting out the first interval, so
 	# the surface isn't visibly empty for half a second on arrival.
diff --git a/RockyPlanetDefinition.tres b/RockyPlanetDefinition.tres
new file mode 100644
index 0000000..b0a3e9f
--- /dev/null
+++ b/RockyPlanetDefinition.tres
@@ -0,0 +1,14 @@
+[gd_resource type="Resource" script_class="PlanetDefinition" load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://PlanetDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://RockyPlanetVisual.tscn" id="2"]
+
+[resource]
+script = ExtResource("1")
+definition_id = "rocky"
+display_name = "Rocky planet"
+names = PackedStringArray("Kepler's Rest", "Ceres Minor", "Vesta's Shadow", "Ironhold", "Drift Anchor", "Stonefall", "Grey Watch", "Silent Quarry", "Baros Rock", "Umbra Point")
+visual_scene = ExtResource("2")
+surface_profile_id = "rocky"
+resource_id = "ore"
+map_color = Color(0.7, 0.65, 0.55, 1)
diff --git a/RockyPlanetVisual.gd b/RockyPlanetVisual.gd
new file mode 100644
index 0000000..dc2a889
--- /dev/null
+++ b/RockyPlanetVisual.gd
@@ -0,0 +1,26 @@
+extends Node2D
+
+var shape_points: PackedVector2Array = PackedVector2Array()
+
+
+func configure(shape_seed: int) -> void:
+	shape_points.clear()
+	var rng := RandomNumberGenerator.new()
+	rng.seed = shape_seed
+	for i in range(10):
+		var angle: float = (float(i) / 10.0) * TAU
+		var radius: float = rng.randf_range(70.0, 100.0)
+		shape_points.append(Vector2(cos(angle), sin(angle)) * radius)
+	queue_redraw()
+
+
+func extractor_anchor() -> Vector2:
+	var anchor := Vector2(0.0, -100.0)
+	for point in shape_points:
+		if point.y < anchor.y:
+			anchor = point
+	return anchor
+
+
+func _draw() -> void:
+	NeonDraw.draw_glowing_polygon(self, shape_points, Color(0.6, 0.55, 0.5), 1.0)
diff --git a/RockyPlanetVisual.gd.uid b/RockyPlanetVisual.gd.uid
new file mode 100644
index 0000000..b6ecadb
--- /dev/null
+++ b/RockyPlanetVisual.gd.uid
@@ -0,0 +1 @@
+uid://b82xh8nosedlm
diff --git a/RockyPlanetVisual.tscn b/RockyPlanetVisual.tscn
new file mode 100644
index 0000000..ee6a302
--- /dev/null
+++ b/RockyPlanetVisual.tscn
@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://RockyPlanetVisual.gd" id="1"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
diff --git a/RockySurfaceFeatures.tscn b/RockySurfaceFeatures.tscn
new file mode 100644
index 0000000..f31b5c8
--- /dev/null
+++ b/RockySurfaceFeatures.tscn
@@ -0,0 +1,7 @@
+[gd_scene load_steps=2 format=3]
+
+[ext_resource type="Script" path="res://RockField.gd" id="1"]
+
+[node name="ResourceProvider" type="Node2D"]
+script = ExtResource("1")
+fleet_path = NodePath("../../Fleet")
diff --git a/RockySurfaceProfile.tres b/RockySurfaceProfile.tres
new file mode 100644
index 0000000..ab220e0
--- /dev/null
+++ b/RockySurfaceProfile.tres
@@ -0,0 +1,14 @@
+[gd_resource type="Resource" script_class="PlanetSurfaceProfile" load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://PlanetSurfaceProfile.gd" id="1"]
+[ext_resource type="PackedScene" path="res://RockySurfaceFeatures.tscn" id="2"]
+
+[resource]
+script = ExtResource("1")
+profile_id = "rocky"
+features_scene = ExtResource("2")
+base_color = Color(0.75, 0.75, 0.76, 1)
+crater_color = Color(0.44, 0.44, 0.45, 1)
+highlight_color = Color(0.89, 0.89, 0.9, 1)
+caption_color = Color(0.08, 0.16, 0.2, 1)
+caption_outline_color = Color(0.9, 0.95, 0.96, 0.8)
diff --git a/ShieldHitsUpgrade.tres b/ShieldHitsUpgrade.tres
new file mode 100644
index 0000000..2530597
--- /dev/null
+++ b/ShieldHitsUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "shd_hits"
+display_name = "Layered Emitters"
+description = "+1 hit absorbed before the shield drops."
+base_cost = 60
+max_level = 2
+icon = 19
+additive_modifiers = {"shield_charges": 1.0}
diff --git a/ShieldRechargeUpgrade.tres b/ShieldRechargeUpgrade.tres
new file mode 100644
index 0000000..d73cf09
--- /dev/null
+++ b/ShieldRechargeUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "shd_recharge"
+display_name = "Fast Cycling"
+description = "Shield returns 1.2s sooner per level."
+base_cost = 35
+max_level = 3
+icon = 20
+additive_modifiers = {"shield_recharge": -1.2}
diff --git a/ShieldSpeedUpgrade.tres b/ShieldSpeedUpgrade.tres
new file mode 100644
index 0000000..fe5a4b6
--- /dev/null
+++ b/ShieldSpeedUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "shd_speed"
+display_name = "Thrusters"
+description = "+40 top speed, +60 acceleration per level."
+base_cost = 25
+max_level = 3
+icon = 18
+additive_modifiers = {"max_speed": 40.0, "acceleration": 60.0}
diff --git a/ShieldVesselDefinition.tres b/ShieldVesselDefinition.tres
new file mode 100644
index 0000000..9df3bf8
--- /dev/null
+++ b/ShieldVesselDefinition.tres
@@ -0,0 +1,25 @@
+[gd_resource type="Resource" script_class="VesselDefinition" load_steps=7 format=3]
+[ext_resource type="Script" path="res://VesselDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://VesselWeaponComponent.tscn" id="2"]
+[ext_resource type="PackedScene" path="res://VesselShieldComponent.tscn" id="3"]
+[ext_resource type="Resource" path="res://ShieldHitsUpgrade.tres" id="4"]
+[ext_resource type="Resource" path="res://ShieldRechargeUpgrade.tres" id="5"]
+[ext_resource type="Resource" path="res://ShieldSpeedUpgrade.tres" id="6"]
+[resource]
+script = ExtResource("1")
+definition_id = "shield"
+display_name = "Shield Vessel"
+description = "Combat vessel whose rechargeable personal shield absorbs lethal impacts."
+build_cost = 14
+build_time = 16.0
+icon = 2
+glow_color = Color(0.45, 0.8, 1, 1)
+capabilities = PackedStringArray("weapon", "shield")
+component_scenes = Array[PackedScene]([ExtResource("2"), ExtResource("3")])
+base_stats = {"damage": 1.0, "fire_cooldown": 0.5, "fire_range": 320.0, "max_speed": 460.0, "acceleration": 450.0, "shield_charges": 1.0, "shield_recharge": 6.0}
+minimum_stats = {"shield_recharge": 2.0}
+upgrades = Array[Resource]([ExtResource("4"), ExtResource("5"), ExtResource("6")])
+unlock_id = "unlock_shield"
+unlock_name = "Unlock Shield Vessel"
+unlock_description = "Lets the ship crafter build shield vessels. Its shield absorbs one lethal hit, then cycles back up."
+unlock_cost = 45
diff --git a/Ship.gd b/Ship.gd
index 624c312..1c2727c 100644
--- a/Ship.gd
+++ b/Ship.gd
@@ -2,224 +2,134 @@ extends Area2D
 
 signal destroyed
 
-# Deliberately faster than Fleet.cruise_speed: the fleet as a whole travels
-# at the cruise rate, and this headroom is what lets an individual ship
-# close on its formation slot - so a pivot mid-flight resolves quickly
-# instead of the ship having no speed budget left over for it.
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
 @export var max_speed: float = 460.0
 @export var acceleration: float = 450.0
 @export var rotation_speed: float = 8.0
 @export var arrive_radius: float = 6.0
-
-@export var fire_range: float = 320.0
-@export var fire_cooldown: float = 0.5
-# How long to wait before looking for targets again after finding none.
-@export var idle_rescan_interval: float = 0.25
-@export var projectile_damage: int = 1
-
-# Which kind of vessel this is (GameState.VESSEL_*). Drives both its
-# researched statistics and whether it carries a shield (#5).
 @export var vessel_type: String = "interceptor"
 
-# --- shield (#5) ----------------------------------------------------------
-const SHIELD_COLOR: Color = Color(0.45, 0.8, 1.0)
-const SHIELD_RADIUS: float = 30.0
-
-# A shield vessel survives a hit that would destroy any other ship, and is
-# then defenceless until it cycles back up. Personal, not a bubble: it
-# protects the vessel carrying it and nothing else.
-var shield_charges: int = 0
-var shield_recharge_left: float = 0.0
-var _shield_ring: Node2D = null
-
-# Neon colours, assigned by Fleet on spawn so a scene can tint its fleet.
-# The lunar surface is a bright grey, where the default near-white core all
-# but vanishes - PlanetSurface.tscn passes a dark core there. See NeonDraw.
+var definition: Resource
 var glow_color: Color = Color(0.25, 0.85, 1.0)
-var core_color: Color = Color(1.0, 1.0, 1.0)
-
+var core_color: Color = Color.WHITE
 var velocity: Vector2 = Vector2.ZERO
-# The fleet's own velocity, supplied by Fleet as CONTEXT rather than as a
-# facing command - the ship works out where to point from it.
-#
-# It is needed because `velocity` below is not the ship's true motion while
-# it is holding formation: the slot it chases sits inside arrive_radius, so
-# the ship snaps onto it and reports zero velocity even though it is being
-# carried along at cruise speed. Facing derived from `velocity` alone
-# therefore froze at whatever heading the ship last happened to travel.
-# Adding the two gives the ship's ACTUAL motion through the world, which is
-# the honest thing to point along in every case: it equals the fleet's
-# heading when station-keeping, the ship's own heading when manoeuvring
-# alone, and the true blend of both while strafing into a new slot.
 var fleet_velocity: Vector2 = Vector2.ZERO
 var move_target: Vector2
-var fire_timer: float = 0.0
-var projectile_scene: PackedScene = preload("res://Projectile.tscn")
+
+# Compatibility accessors keep old saves/tests readable while shield state
+# itself belongs exclusively to the optional ShieldComponent.
+var shield_charges: int:
+	get:
+		var component: Node = get_component("shield")
+		return component.charges if component != null else 0
+	set(value):
+		var component: Node = get_component("shield")
+		if component != null:
+			component.set_charges(value)
+
+var shield_recharge_left: float:
+	get:
+		var component: Node = get_component("shield")
+		return component.recharge_left if component != null else 0.0
+	set(value):
+		var component: Node = get_component("shield")
+		if component != null:
+			component.recharge_left = value
+
+var projectile_damage: int:
+	get:
+		var component: Node = get_component("weapon")
+		return component.projectile_damage if component != null else 0
 
 
 func _ready() -> void:
 	move_target = position
 	add_to_group("player_ships")
 	area_entered.connect(_on_area_entered)
-	if vessel_type == GameState.VESSEL_SHIELD:
-		_build_shield_ring()
-		shield_charges = GameState.shield_max_charges()
+	definition = VESSEL_DEFINITIONS.get_definition(vessel_type)
+	if definition == null:
+		return
+	glow_color = definition.glow_color
+	for component_scene in definition.component_scenes:
+		var component: Node = component_scene.instantiate()
+		add_child(component)
+		if component.has_method("setup"):
+			component.setup()
 	apply_vessel_stats()
 	queue_redraw()
 
 
+func get_component(capability: String) -> Node:
+	for child in get_children():
+		if child.get("capability_id") == capability:
+			return child
+	return null
+
+
+func has_capability(capability: String) -> bool:
+	return get_component(capability) != null
+
+
 func set_move_target(world_pos: Vector2) -> void:
 	move_target = world_pos
 
 
 func apply_vessel_stats() -> void:
-	# Read from GameState rather than baked in at spawn, so researching an
-	# upgrade improves the ships already flying and not just the next one
-	# built. Fleet calls this on every vessel when something is bought.
-	max_speed = GameState.ship_max_speed(vessel_type)
-	acceleration = GameState.ship_acceleration(vessel_type)
-	fire_range = GameState.ship_fire_range(vessel_type)
-	fire_cooldown = GameState.ship_fire_cooldown(vessel_type)
-	projectile_damage = GameState.ship_damage(vessel_type)
-	if vessel_type == GameState.VESSEL_SHIELD:
-		# Topping up a live shield with researched capacity, without
-		# refilling one that is currently down and cycling.
-		var was_up: bool = shield_charges > 0
-		shield_charges = GameState.shield_max_charges() if was_up else shield_charges
-	_update_shield_visual()
+	if definition == null:
+		definition = VESSEL_DEFINITIONS.get_definition(vessel_type)
+	if definition == null:
+		return
+	max_speed = GameState.vessel_stat(vessel_type, "max_speed")
+	acceleration = GameState.vessel_stat(vessel_type, "acceleration")
+	for child in get_children():
+		if child.has_method("apply_stats"):
+			child.apply_stats()
 
 
 func has_shield() -> bool:
-	return vessel_type == GameState.VESSEL_SHIELD and shield_charges > 0
-
-
-func _update_shield_visual() -> void:
-	if _shield_ring == null:
-		return
-	# visible only - per #10 the ring is rasterised once and never redrawn to
-	# turn it on and off.
-	_shield_ring.visible = has_shield()
-
-
-func _tick_shield(delta: float) -> void:
-	if vessel_type != GameState.VESSEL_SHIELD:
-		return
-	if shield_charges >= GameState.shield_max_charges():
-		return
-	shield_recharge_left -= delta
-	if shield_recharge_left <= 0.0:
-		shield_charges += 1
-		shield_recharge_left = GameState.shield_recharge_time()
-		_update_shield_visual()
+	var component: Node = get_component("shield")
+	return component != null and component.is_active()
 
 
 func _physics_process(delta: float) -> void:
-	_tick_shield(delta)
+	for child in get_children():
+		if child.has_method("tick"):
+			child.tick(delta)
+
 	var to_target: Vector2 = move_target - position
 	var distance: float = to_target.length()
-
 	if distance <= arrive_radius:
-		# Snap and stop dead - prevents residual float-level jitter that
-		# would otherwise keep nudging back and forth around the target.
 		position = move_target
 		velocity = Vector2.ZERO
 	else:
-		# Braking-distance formula: the fastest speed we can be going right
-		# now and still be able to decelerate to 0 exactly at the target,
-		# given our acceleration. Without this the ship approaches at full
-		# speed, overshoots (stopping distance = max_speed^2 / (2*accel)),
-		# and oscillates back and forth forever instead of settling.
 		var braking_speed: float = sqrt(2.0 * acceleration * distance)
 		var desired_speed: float = min(max_speed, braking_speed)
 		var desired_velocity: Vector2 = to_target.normalized() * desired_speed
 		velocity = velocity.move_toward(desired_velocity, acceleration * delta)
 		position += velocity * delta
 
-	# One owner, one rule: face the way this ship is actually travelling.
 	var motion: Vector2 = velocity + fleet_velocity
 	if motion.length() > 8.0:
 		var target_angle: float = motion.angle() + PI / 2.0
 		rotation = lerp_angle(rotation, target_angle, rotation_speed * delta)
 
-	_update_weapon(delta)
-
-
-func _update_weapon(delta: float) -> void:
-	fire_timer -= delta
-	if fire_timer > 0.0:
-		return
-
-	var target: Node2D = _find_nearest_enemy()
-	if target == null:
-		# Back off before scanning again. Without this, fire_timer stays at
-		# or below zero and every ship queries the whole "enemies" group and
-		# loops it on EVERY physics frame whenever nothing is in range -
-		# which is most of the time.
-		fire_timer = idle_rescan_interval
-		return
-
-	fire_timer = fire_cooldown
-	var proj: Node2D = projectile_scene.instantiate()
-	proj.position = position
-	proj.damage = projectile_damage
-	get_tree().root.add_child(proj)
-	proj.launch(target.position - position)
-
-
-func _find_nearest_enemy() -> Node2D:
-	var enemies: Array = get_tree().get_nodes_in_group("enemies")
-	var nearest: Node2D = null
-	var best_dist: float = fire_range
-
-	for e in enemies:
-		if not is_instance_valid(e):
-			continue
-		var d: float = position.distance_to(e.position)
-		if d <= best_dist:
-			best_dist = d
-			nearest = e
-
-	return nearest
-
 
 func _on_area_entered(area: Area2D) -> void:
 	if not (area.is_in_group("enemies") or area.is_in_group("asteroids")):
 		return
-	if has_shield():
-		# Absorbed. The thing that hit it is still destroyed - a shield stops
-		# the vessel dying, it does not make the rock harmless - but the
-		# vessel survives and is defenceless until the shield cycles back.
-		shield_charges -= 1
-		shield_recharge_left = GameState.shield_recharge_time()
-		_update_shield_visual()
-		if area.is_in_group("asteroids") and is_instance_valid(area):
-			area.queue_free()
-		return
+	for child in get_children():
+		if child.has_method("absorb_hit") and child.absorb_hit():
+			if area.is_in_group("asteroids") and is_instance_valid(area):
+				area.queue_free()
+			return
 	ShipExplosionVFX.spawn(get_tree().root, position)
 	destroyed.emit()
 	queue_free()
 
 
-func _build_shield_ring() -> void:
-	# Its own child, drawn once, toggled with `visible` (#10). A shield that
-	# came and went by redrawing the ship would re-tessellate the hull every
-	# time it cycled.
-	_shield_ring = NeonPiece.create(self, Vector2.ZERO, SHIELD_COLOR)
-	var points: PackedVector2Array = PackedVector2Array()
-	for i in range(14):
-		var a: float = (float(i) / 14.0) * TAU
-		points.append(Vector2(cos(a), sin(a)) * SHIELD_RADIUS)
-	_shield_ring.add_polygon(points, 0.7)
-	_shield_ring.queue_redraw()
-	_shield_ring.visible = false
-
-
 func _draw() -> void:
-	var nose: Vector2 = Vector2(0, -22)
-	var left: Vector2 = Vector2(-14, 16)
-	var right: Vector2 = Vector2(14, 16)
-	var points: PackedVector2Array = PackedVector2Array([nose, left, right])
-	# Constant glow, drawn once. No pulse means nothing changes frame to
-	# frame, so the ship never needs redrawing after _ready() - which also
-	# removes four antialiased polyline rebuilds per ship per frame.
+	var points: PackedVector2Array = definition.hull_points if definition != null else PackedVector2Array([
+		Vector2(0, -22), Vector2(-14, 16), Vector2(14, 16),
+	])
 	NeonDraw.draw_glowing_polygon(self, points, glow_color, 1.0, core_color)
diff --git a/ShipLabBuildingDefinition.tres b/ShipLabBuildingDefinition.tres
new file mode 100644
index 0000000..0823f52
--- /dev/null
+++ b/ShipLabBuildingDefinition.tres
@@ -0,0 +1,20 @@
+[gd_resource type="Resource" script_class="BuildingDefinition" load_steps=3 format=3]
+[ext_resource type="Script" path="res://BuildingDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://ShipLabBuildingVisual.tscn" id="2"]
+[resource]
+script = ExtResource("1")
+definition_id = "ship_lab"
+display_name = "Ship Lab"
+description = "Fly the fleet onto it to upgrade each vessel type and unlock new vessel designs."
+cost = 35
+action_icon = 13
+menu_icon = 13
+visual_scene = ExtResource("2")
+capabilities = PackedStringArray("vessel_research")
+map_color = Color(0.55, 0.95, 0.9, 1)
+map_sides = 3
+map_radius = 7.5
+map_phase = -1.570796
+menu_button_name = "ShipLabButton"
+menu_label_name = "ShipLabLabel"
+menu_cost_name = "ShipLabCost"
diff --git a/ShipLabBuildingVisual.gd b/ShipLabBuildingVisual.gd
new file mode 100644
index 0000000..9655162
--- /dev/null
+++ b/ShipLabBuildingVisual.gd
@@ -0,0 +1,12 @@
+extends "res://BuildingVisualBase.gd"
+
+func _ready() -> void:
+	_build_lab_pieces()
+	queue_redraw()
+
+func apply_animation() -> void:
+	_animate_ship_lab()
+
+func _draw() -> void:
+	register_draw()
+	_draw_ship_lab_static(self)
diff --git a/ShipLabBuildingVisual.gd.uid b/ShipLabBuildingVisual.gd.uid
new file mode 100644
index 0000000..fbb5203
--- /dev/null
+++ b/ShipLabBuildingVisual.gd.uid
@@ -0,0 +1 @@
+uid://b0p7p0fs0th0b
diff --git a/ShipLabBuildingVisual.tscn b/ShipLabBuildingVisual.tscn
new file mode 100644
index 0000000..e71fdf2
--- /dev/null
+++ b/ShipLabBuildingVisual.tscn
@@ -0,0 +1,11 @@
+[gd_scene load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://ShipLabBuildingVisual.gd" id="1"]
+[ext_resource type="Script" path="res://BuildingActionProvider.gd" id="2"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
+
+[node name="ActionProvider" type="Node" parent="."]
+script = ExtResource("2")
+actions = PackedStringArray("lab", "transfer")
diff --git a/TransportCapacityUpgrade.tres b/TransportCapacityUpgrade.tres
new file mode 100644
index 0000000..2c2b920
--- /dev/null
+++ b/TransportCapacityUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "trn_capacity"
+display_name = "Expanded Hold"
+description = "Carries 8 more resources per supply run."
+base_cost = 30
+max_level = 3
+icon = 21
+additive_modifiers = {"cargo_capacity": 8.0}
diff --git a/TransportHubBuildingDefinition.tres b/TransportHubBuildingDefinition.tres
new file mode 100644
index 0000000..59ad15d
--- /dev/null
+++ b/TransportHubBuildingDefinition.tres
@@ -0,0 +1,20 @@
+[gd_resource type="Resource" script_class="BuildingDefinition" load_steps=3 format=3]
+[ext_resource type="Script" path="res://BuildingDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://TransportHubBuildingVisual.tscn" id="2"]
+[resource]
+script = ExtResource("1")
+definition_id = "transport_hub"
+display_name = "Transport Hub"
+description = "Stations transport vessels. They collect extracted resources and supply buildings that are waiting on materials."
+cost = 30
+action_icon = 12
+menu_icon = 12
+visual_scene = ExtResource("2")
+capabilities = PackedStringArray("transport_hub")
+map_color = Color(0.95, 0.55, 0.85, 1)
+map_sides = 8
+map_radius = 7.5
+map_phase = 0.392699
+menu_button_name = "TransportHubButton"
+menu_label_name = "TransportHubLabel"
+menu_cost_name = "TransportHubCost"
diff --git a/TransportHubBuildingVisual.gd b/TransportHubBuildingVisual.gd
new file mode 100644
index 0000000..a8a0d44
--- /dev/null
+++ b/TransportHubBuildingVisual.gd
@@ -0,0 +1,12 @@
+extends "res://BuildingVisualBase.gd"
+
+func _ready() -> void:
+	_build_hub_pieces()
+	queue_redraw()
+
+func apply_animation() -> void:
+	_animate_transport_hub()
+
+func _draw() -> void:
+	register_draw()
+	_draw_transport_hub_static(self)
diff --git a/TransportHubBuildingVisual.gd.uid b/TransportHubBuildingVisual.gd.uid
new file mode 100644
index 0000000..b1ca4cb
--- /dev/null
+++ b/TransportHubBuildingVisual.gd.uid
@@ -0,0 +1 @@
+uid://6qyl5qnhw0ho
diff --git a/TransportHubBuildingVisual.tscn b/TransportHubBuildingVisual.tscn
new file mode 100644
index 0000000..1426761
--- /dev/null
+++ b/TransportHubBuildingVisual.tscn
@@ -0,0 +1,11 @@
+[gd_scene load_steps=3 format=3]
+
+[ext_resource type="Script" path="res://TransportHubBuildingVisual.gd" id="1"]
+[ext_resource type="Script" path="res://BuildingActionProvider.gd" id="2"]
+
+[node name="Visual" type="Node2D"]
+script = ExtResource("1")
+
+[node name="ActionProvider" type="Node" parent="."]
+script = ExtResource("2")
+actions = PackedStringArray("transfer")
diff --git a/TransportSpeedUpgrade.tres b/TransportSpeedUpgrade.tres
new file mode 100644
index 0000000..43c3c96
--- /dev/null
+++ b/TransportSpeedUpgrade.tres
@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="VesselUpgradeDefinition" load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselUpgradeDefinition.gd" id="1"]
+[resource]
+script = ExtResource("1")
+upgrade_id = "trn_speed"
+display_name = "Freight Engines"
+description = "+70 speed on supply runs."
+base_cost = 30
+max_level = 3
+icon = 22
+additive_modifiers = {"transport_speed": 70.0}
diff --git a/TransporterVesselDefinition.tres b/TransporterVesselDefinition.tres
new file mode 100644
index 0000000..c654a48
--- /dev/null
+++ b/TransporterVesselDefinition.tres
@@ -0,0 +1,19 @@
+[gd_resource type="Resource" script_class="VesselDefinition" load_steps=6 format=3]
+[ext_resource type="Script" path="res://VesselDefinition.gd" id="1"]
+[ext_resource type="PackedScene" path="res://VesselCargoComponent.tscn" id="2"]
+[ext_resource type="PackedScene" path="res://VesselTransportComponent.tscn" id="3"]
+[ext_resource type="Resource" path="res://TransportCapacityUpgrade.tres" id="4"]
+[ext_resource type="Resource" path="res://TransportSpeedUpgrade.tres" id="5"]
+[resource]
+script = ExtResource("1")
+definition_id = "transporter"
+display_name = "Transporter"
+description = "Unarmed cargo vessel stationed at a transport hub to move resources."
+build_cost = 10
+build_time = 8.0
+icon = 12
+glow_color = Color(0.95, 0.55, 0.85, 1)
+capabilities = PackedStringArray("cargo", "transport")
+component_scenes = Array[PackedScene]([ExtResource("2"), ExtResource("3")])
+base_stats = {"max_speed": 460.0, "acceleration": 450.0, "cargo_capacity": 20.0, "transport_speed": 340.0}
+upgrades = Array[Resource]([ExtResource("4"), ExtResource("5")])
diff --git a/VesselCargoComponent.gd b/VesselCargoComponent.gd
new file mode 100644
index 0000000..4373500
--- /dev/null
+++ b/VesselCargoComponent.gd
@@ -0,0 +1,9 @@
+class_name VesselCargoComponent
+extends Node
+
+var capability_id: String = "cargo"
+var capacity: int
+
+func apply_stats() -> void:
+	var state: Node = get_tree().root.get_node("GameState")
+	capacity = int(state.vessel_stat(get_parent().vessel_type, "cargo_capacity"))
diff --git a/VesselCargoComponent.gd.uid b/VesselCargoComponent.gd.uid
new file mode 100644
index 0000000..85443bc
--- /dev/null
+++ b/VesselCargoComponent.gd.uid
@@ -0,0 +1 @@
+uid://bo16x4wq6hg5k
diff --git a/VesselCargoComponent.tscn b/VesselCargoComponent.tscn
new file mode 100644
index 0000000..34eafa6
--- /dev/null
+++ b/VesselCargoComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselCargoComponent.gd" id="1"]
+[node name="CargoComponent" type="Node"]
+script = ExtResource("1")
diff --git a/VesselDefinition.gd b/VesselDefinition.gd
new file mode 100644
index 0000000..0f6637f
--- /dev/null
+++ b/VesselDefinition.gd
@@ -0,0 +1,26 @@
+class_name VesselDefinition
+extends Resource
+
+@export var definition_id: String
+@export var display_name: String
+@export_multiline var description: String
+@export var build_cost: int
+@export var build_time: float = 10.0
+@export var icon: int = 2
+@export var glow_color: Color = Color(0.25, 0.85, 1.0)
+@export var hull_points: PackedVector2Array = PackedVector2Array([
+	Vector2(0, -22), Vector2(-14, 16), Vector2(14, 16),
+])
+@export var capabilities: PackedStringArray = []
+@export var component_scenes: Array[PackedScene] = []
+@export var base_stats: Dictionary = {}
+@export var minimum_stats: Dictionary = {}
+@export var upgrades: Array[Resource] = []
+@export var unlock_id: String
+@export var unlock_name: String
+@export_multiline var unlock_description: String
+@export var unlock_cost: int
+
+
+func has_capability(capability: String) -> bool:
+	return capability in capabilities
diff --git a/VesselDefinition.gd.uid b/VesselDefinition.gd.uid
new file mode 100644
index 0000000..371e084
--- /dev/null
+++ b/VesselDefinition.gd.uid
@@ -0,0 +1 @@
+uid://c6txy3v61blm8
diff --git a/VesselDefinitions.gd b/VesselDefinitions.gd
new file mode 100644
index 0000000..2b33845
--- /dev/null
+++ b/VesselDefinitions.gd
@@ -0,0 +1,24 @@
+class_name VesselDefinitions
+extends RefCounted
+
+const ORDER: PackedStringArray = ["interceptor", "shield", "transporter"]
+const DEFINITIONS: Dictionary = {
+	"interceptor": preload("res://InterceptorVesselDefinition.tres"),
+	"shield": preload("res://ShieldVesselDefinition.tres"),
+	"transporter": preload("res://TransporterVesselDefinition.tres"),
+}
+
+static func get_definition(definition_id: String) -> Resource:
+	return DEFINITIONS.get(definition_id)
+
+static func all() -> Array:
+	var result: Array = []
+	for definition_id in ORDER:
+		result.append(DEFINITIONS[definition_id])
+	return result
+
+static func with_capability(capability: String) -> Resource:
+	for definition in all():
+		if definition.has_capability(capability):
+			return definition
+	return null
diff --git a/VesselDefinitions.gd.uid b/VesselDefinitions.gd.uid
new file mode 100644
index 0000000..d907359
--- /dev/null
+++ b/VesselDefinitions.gd.uid
@@ -0,0 +1 @@
+uid://cgwj1q4nf3ar7
diff --git a/VesselDelivery.gd b/VesselDelivery.gd
index 4c07a6d..6392b62 100644
--- a/VesselDelivery.gd
+++ b/VesselDelivery.gd
@@ -1,8 +1,10 @@
 extends Node2D
 
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
 # Visual-only craft-to-mothership flight. GameState owns position/progress;
 # this node just renders a finished hull headed toward the hangar.
-var vessel_type: String = GameState.VESSEL_INTERCEPTOR
+var vessel_type: String = "interceptor"
 
 
 func _ready() -> void:
@@ -11,6 +13,6 @@ func _ready() -> void:
 
 
 func _draw() -> void:
-	var color: Color = Color(0.45, 0.8, 1.0) if vessel_type == GameState.VESSEL_SHIELD else Color(0.95, 0.55, 0.85) if vessel_type == GameState.VESSEL_TRANSPORTER else Color(0.25, 0.85, 1.0)
-	var hull := PackedVector2Array([Vector2(0, -20), Vector2(13, 15), Vector2(0, 9), Vector2(-13, 15)])
-	NeonDraw.draw_glowing_polygon(self, hull, color, 1.0)
+	var definition: Resource = VESSEL_DEFINITIONS.get_definition(vessel_type)
+	if definition != null:
+		NeonDraw.draw_glowing_polygon(self, definition.hull_points, definition.glow_color, 1.0)
diff --git a/VesselDeliveryField.gd b/VesselDeliveryField.gd
index 606b1cf..9b47319 100644
--- a/VesselDeliveryField.gd
+++ b/VesselDeliveryField.gd
@@ -17,9 +17,9 @@ func _process(_delta: float) -> void:
 		var node: Node2D = active.get(i)
 		if node == null or not is_instance_valid(node):
 			node = delivery_script.new()
+			node.vessel_type = String(delivery.type)
 			get_parent().add_child(node)
 			active[i] = node
-		node.vessel_type = String(delivery.type)
 		node.position = pos
 		var direction: Vector2 = (delivery.to as Vector2) - (delivery.from as Vector2)
 		if direction.length() > 0.1:
diff --git a/VesselShieldComponent.gd b/VesselShieldComponent.gd
new file mode 100644
index 0000000..15a8edf
--- /dev/null
+++ b/VesselShieldComponent.gd
@@ -0,0 +1,69 @@
+class_name VesselShieldComponent
+extends Node
+
+const SHIELD_COLOR: Color = Color(0.45, 0.8, 1.0)
+const SHIELD_RADIUS: float = 30.0
+
+var capability_id: String = "shield"
+var charges: int = 0
+var recharge_left: float = 0.0
+var ring: Node2D
+
+
+func setup() -> void:
+	var ship: Node2D = get_parent()
+	var state: Node = ship.get_tree().root.get_node("GameState")
+	ring = NeonPiece.create(ship, Vector2.ZERO, SHIELD_COLOR)
+	var points := PackedVector2Array()
+	for i in range(14):
+		var angle: float = float(i) / 14.0 * TAU
+		points.append(Vector2(cos(angle), sin(angle)) * SHIELD_RADIUS)
+	ring.add_polygon(points, 0.7)
+	ring.queue_redraw()
+	charges = int(state.vessel_stat(ship.vessel_type, "shield_charges"))
+	_update_visual()
+
+
+func apply_stats() -> void:
+	var was_up: bool = charges > 0
+	if was_up:
+		charges = int(_state().vessel_stat(get_parent().vessel_type, "shield_charges"))
+	_update_visual()
+
+
+func tick(delta: float) -> void:
+	var maximum: int = int(_state().vessel_stat(get_parent().vessel_type, "shield_charges"))
+	if charges >= maximum:
+		return
+	recharge_left -= delta
+	if recharge_left <= 0.0:
+		charges += 1
+		recharge_left = _state().vessel_stat(get_parent().vessel_type, "shield_recharge")
+		_update_visual()
+
+
+func is_active() -> bool:
+	return charges > 0
+
+
+func absorb_hit() -> bool:
+	if not is_active():
+		return false
+	charges -= 1
+	recharge_left = _state().vessel_stat(get_parent().vessel_type, "shield_recharge")
+	_update_visual()
+	return true
+
+
+func set_charges(value: int) -> void:
+	charges = value
+	_update_visual()
+
+
+func _state() -> Node:
+	return get_tree().root.get_node("GameState")
+
+
+func _update_visual() -> void:
+	if ring != null:
+		ring.visible = is_active()
diff --git a/VesselShieldComponent.gd.uid b/VesselShieldComponent.gd.uid
new file mode 100644
index 0000000..4ab2382
--- /dev/null
+++ b/VesselShieldComponent.gd.uid
@@ -0,0 +1 @@
+uid://ghacatobxl11
diff --git a/VesselShieldComponent.tscn b/VesselShieldComponent.tscn
new file mode 100644
index 0000000..50ba89e
--- /dev/null
+++ b/VesselShieldComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselShieldComponent.gd" id="1"]
+[node name="ShieldComponent" type="Node"]
+script = ExtResource("1")
diff --git a/VesselTransportComponent.gd b/VesselTransportComponent.gd
new file mode 100644
index 0000000..7aec619
--- /dev/null
+++ b/VesselTransportComponent.gd
@@ -0,0 +1,9 @@
+class_name VesselTransportComponent
+extends Node
+
+var capability_id: String = "transport"
+var travel_speed: float
+
+func apply_stats() -> void:
+	var state: Node = get_tree().root.get_node("GameState")
+	travel_speed = state.vessel_stat(get_parent().vessel_type, "transport_speed")
diff --git a/VesselTransportComponent.gd.uid b/VesselTransportComponent.gd.uid
new file mode 100644
index 0000000..a2c81fd
--- /dev/null
+++ b/VesselTransportComponent.gd.uid
@@ -0,0 +1 @@
+uid://tsapg8ld1vl8
diff --git a/VesselTransportComponent.tscn b/VesselTransportComponent.tscn
new file mode 100644
index 0000000..a16d4e9
--- /dev/null
+++ b/VesselTransportComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselTransportComponent.gd" id="1"]
+[node name="TransportComponent" type="Node"]
+script = ExtResource("1")
diff --git a/VesselUpgradeDefinition.gd b/VesselUpgradeDefinition.gd
new file mode 100644
index 0000000..083e092
--- /dev/null
+++ b/VesselUpgradeDefinition.gd
@@ -0,0 +1,11 @@
+class_name VesselUpgradeDefinition
+extends Resource
+
+@export var upgrade_id: String
+@export var display_name: String
+@export_multiline var description: String
+@export var base_cost: int
+@export var max_level: int = 1
+@export var icon: int
+@export var additive_modifiers: Dictionary = {}
+@export var multiplicative_modifiers: Dictionary = {}
diff --git a/VesselUpgradeDefinition.gd.uid b/VesselUpgradeDefinition.gd.uid
new file mode 100644
index 0000000..c615214
--- /dev/null
+++ b/VesselUpgradeDefinition.gd.uid
@@ -0,0 +1 @@
+uid://dw41jux1cn3sw
diff --git a/VesselWeaponComponent.gd b/VesselWeaponComponent.gd
new file mode 100644
index 0000000..1bc6855
--- /dev/null
+++ b/VesselWeaponComponent.gd
@@ -0,0 +1,47 @@
+class_name VesselWeaponComponent
+extends Node
+
+var capability_id: String = "weapon"
+var fire_range: float
+var fire_cooldown: float
+var projectile_damage: int
+var fire_timer: float = 0.0
+var projectile_scene: PackedScene = preload("res://Projectile.tscn")
+
+
+func apply_stats() -> void:
+	var ship: Node = get_parent()
+	var state: Node = ship.get_tree().root.get_node("GameState")
+	fire_range = state.vessel_stat(ship.vessel_type, "fire_range")
+	fire_cooldown = state.vessel_stat(ship.vessel_type, "fire_cooldown")
+	projectile_damage = int(state.vessel_stat(ship.vessel_type, "damage"))
+
+
+func tick(delta: float) -> void:
+	fire_timer -= delta
+	if fire_timer > 0.0:
+		return
+	var ship: Node2D = get_parent()
+	var target: Node2D = _find_nearest_enemy(ship)
+	if target == null:
+		fire_timer = 0.25
+		return
+	var projectile: Node2D = projectile_scene.instantiate()
+	projectile.position = ship.position
+	projectile.damage = projectile_damage
+	ship.get_tree().root.add_child(projectile)
+	projectile.launch(target.position - ship.position)
+	fire_timer = fire_cooldown
+
+
+func _find_nearest_enemy(ship: Node2D) -> Node2D:
+	var nearest: Node2D = null
+	var best_distance: float = fire_range
+	for enemy in ship.get_tree().get_nodes_in_group("enemies"):
+		if not is_instance_valid(enemy):
+			continue
+		var distance: float = ship.position.distance_to(enemy.position)
+		if distance <= best_distance:
+			best_distance = distance
+			nearest = enemy
+	return nearest
diff --git a/VesselWeaponComponent.gd.uid b/VesselWeaponComponent.gd.uid
new file mode 100644
index 0000000..9fd5306
--- /dev/null
+++ b/VesselWeaponComponent.gd.uid
@@ -0,0 +1 @@
+uid://cwo0nkmr4e1sl
diff --git a/VesselWeaponComponent.tscn b/VesselWeaponComponent.tscn
new file mode 100644
index 0000000..b3bd611
--- /dev/null
+++ b/VesselWeaponComponent.tscn
@@ -0,0 +1,4 @@
+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://VesselWeaponComponent.gd" id="1"]
+[node name="WeaponComponent" type="Node"]
+script = ExtResource("1")
diff --git a/WorldGen.gd b/WorldGen.gd
index e36a51f..5e73ee5 100644
--- a/WorldGen.gd
+++ b/WorldGen.gd
@@ -1,6 +1,8 @@
 class_name WorldGen
 extends RefCounted
 
+const PLANET_DEFINITIONS = preload("res://PlanetDefinitions.gd")
+
 # Deterministic procedural world generation: the world is divided into
 # square chunks, and each chunk's biome is derived from a seeded
 # low-frequency noise field sampled at the chunk's own coordinates - so
@@ -22,13 +24,6 @@ const GAS_GIANT_THRESHOLD: float = 0.55
 const NEARBY_GAS_GIANT_CHUNK: Vector2i = Vector2i.ZERO
 const NEARBY_GAS_GIANT_LOCAL_POS: Vector2 = Vector2(900.0, 600.0)
 
-const PLANET_NAMES: Array = [
-	"Kepler's Rest", "Ceres Minor", "Vesta's Shadow", "Ironhold",
-	"Drift Anchor", "Stonefall", "Grey Watch", "Silent Quarry",
-	"Baros Rock", "Umbra Point",
-]
-const GAS_GIANT_NAMES: Array = ["Aurelia", "Boreas", "Cerulean Deep", "Helios Major", "Vesper"]
-
 static var _noise: FastNoiseLite
 static var _planet_noise: FastNoiseLite
 
@@ -88,15 +83,16 @@ static func planet_data_at_chunk(chunk: Vector2i) -> Dictionary:
 	var guaranteed_nearby_giant: bool = chunk == NEARBY_GAS_GIANT_CHUNK
 	var local_pos: Vector2 = NEARBY_GAS_GIANT_LOCAL_POS if guaranteed_nearby_giant \
 		else Vector2(rng.randf() * CHUNK_SIZE, rng.randf() * CHUNK_SIZE)
-	var planet_name: String = PLANET_NAMES[rng.randi() % PLANET_NAMES.size()]
 	var shape_seed: int = rng.randi()
 	# A stable per-chunk roll makes gas giants persistent landmarks rather
 	# than a different resource whenever the scene reloads.
 	var gas_giant: bool = guaranteed_nearby_giant or biome_at_chunk(chunk) == Biome.SPACE
-	if gas_giant:
-		planet_name = GAS_GIANT_NAMES[rng.randi() % GAS_GIANT_NAMES.size()]
+	var definition_id: String = PLANET_DEFINITIONS.GAS_GIANT_ID if gas_giant else PLANET_DEFINITIONS.ROCKY_ID
+	var definition: Resource = PLANET_DEFINITIONS.get_definition(definition_id)
+	var names: PackedStringArray = definition.names
+	var planet_name: String = names[rng.randi() % names.size()]
 	return {"local_pos": local_pos, "name": planet_name, "shape_seed": shape_seed,
-		"planet_type": "gas_giant" if gas_giant else "rocky", "resource_type": "gas" if gas_giant else "ore"}
+		"definition_id": definition_id}
 
 
 static func biome_color(biome: int) -> Color:
diff --git a/WorldMapContent.gd b/WorldMapContent.gd
index e8ba8df..5d4667b 100644
--- a/WorldMapContent.gd
+++ b/WorldMapContent.gd
@@ -1,17 +1,9 @@
 extends Node2D
 
-const WORLD_TO_LOCAL: float = 0.04
+const PLANET_DEFINITIONS = preload("res://PlanetDefinitions.gd")
+const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
 
-# Mirrors Building.gd's own MOTHERSHIP_COLOR/CRAFTER_COLOR/COMMAND_COLOR so a
-# marker on the map reads as "the same building" at a glance. Duplicated
-# rather than cross-referenced - the same colour is already independently
-# duplicated between Ship.gd, Fleet.gd and Building.gd's HULL_COLOR, so this
-# follows the codebase's existing convention rather than inventing a new one.
-const MOTHERSHIP_MARKER_COLOR: Color = Color(0.45, 0.9, 0.55)
-const CRAFTER_MARKER_COLOR: Color = Color(1.0, 0.72, 0.25)
-const COMMAND_MARKER_COLOR: Color = Color(0.55, 0.6, 1.0)
-const TRANSPORT_HUB_MARKER_COLOR: Color = Color(0.95, 0.55, 0.85)
-const SHIP_LAB_MARKER_COLOR: Color = Color(0.55, 0.95, 0.9)
+const WORLD_TO_LOCAL: float = 0.04
 
 # A structure built on a planet's surface (see GameState.extractors) is not
 # itself a map marker - it is a small badge on the existing planet marker,
@@ -38,28 +30,20 @@ func _process(_delta: float) -> void:
 func building_markers() -> Array:
 	var markers: Array = []
 	for b in GameState.buildings:
+		var definition: Resource = BUILDING_DEFINITIONS.get_definition(String(b.type))
+		if definition == null:
+			continue
 		markers.append({
 			"position": b.position * WORLD_TO_LOCAL,
 			"type": b.type,
-			"color": _building_marker_color(b.type),
+			"color": definition.map_color,
+			"sides": definition.map_sides,
+			"radius": definition.map_radius,
+			"phase": definition.map_phase,
 		})
 	return markers
 
 
-func _building_marker_color(type: String) -> Color:
-	match type:
-		GameState.BUILDING_MOTHERSHIP:
-			return MOTHERSHIP_MARKER_COLOR
-		GameState.BUILDING_SHIP_CRAFTER:
-			return CRAFTER_MARKER_COLOR
-		GameState.BUILDING_TRANSPORT_HUB:
-			return TRANSPORT_HUB_MARKER_COLOR
-		GameState.BUILDING_SHIP_LAB:
-			return SHIP_LAB_MARKER_COLOR
-		_:
-			return COMMAND_MARKER_COLOR
-
-
 # Whether the planet in this (explored) chunk has an extractor on it, per
 # GameState.has_extractor_at(). A separate predicate for the same
 # GPU-less-testability reason as building_markers().
@@ -105,7 +89,8 @@ func _draw() -> void:
 			# spawn_radius_chunks of the fleet).
 			var data: Dictionary = WorldGen.planet_data_at_chunk(chunk)
 			var planet_local: Vector2 = origin_local + data.local_pos * WORLD_TO_LOCAL
-			draw_circle(planet_local, 5.0, Color(0.7, 0.65, 0.55))
+			var definition: Resource = PLANET_DEFINITIONS.get_definition(String(data.definition_id))
+			draw_circle(planet_local, 5.0, definition.map_color)
 			draw_arc(planet_local, 5.0, 0.0, TAU, 16, Color(1.0, 1.0, 1.0, 0.9), 1.0, true)
 
 			if chunk_has_extractor_badge(chunk):
@@ -116,17 +101,7 @@ func _draw() -> void:
 	# Buildings are placed freely in space rather than tied to a chunk, so
 	# they get their own pass rather than living inside the chunk loop above.
 	for marker in building_markers():
-		match marker.type:
-			GameState.BUILDING_MOTHERSHIP:
-				_draw_marker_polygon(_regular_polygon(marker.position, 8.0, 6, PI / 6.0), marker.color)
-			GameState.BUILDING_SHIP_CRAFTER:
-				_draw_marker_polygon(_regular_polygon(marker.position, 7.0, 4, 0.0), marker.color)
-			GameState.BUILDING_TRANSPORT_HUB:
-				_draw_marker_polygon(_regular_polygon(marker.position, 7.5, 8, PI / 8.0), marker.color)
-			GameState.BUILDING_SHIP_LAB:
-				_draw_marker_polygon(_regular_polygon(marker.position, 7.5, 3, -PI / 2.0), marker.color)
-			_:
-				_draw_marker_polygon(_regular_polygon(marker.position, 6.0, 4, PI / 4.0), marker.color)
+		_draw_marker_polygon(_regular_polygon(marker.position, marker.radius, marker.sides, marker.phase), marker.color)
 
 	var fleet_local: Vector2 = fleet.get_centroid() * WORLD_TO_LOCAL
 	var marker_points: PackedVector2Array = PackedVector2Array([
diff --git a/tests/_build_popup_preview.gd b/tests/_build_popup_preview.gd
index 3bb938e..d3c6b1d 100644
--- a/tests/_build_popup_preview.gd
+++ b/tests/_build_popup_preview.gd
@@ -28,4 +28,4 @@ func _ready() -> void:
 	# Flip SHOW_POPUP to check the menu underneath
 	# instead of the popup that covers it.
 	if SHOW_POPUP:
-		controller._on_place_mothership()
+		controller._show_building_info(GameState.BUILDING_MOTHERSHIP)
diff --git a/tests/_crafter_preview.gd b/tests/_crafter_preview.gd
index dc89fe4..52888aa 100644
--- a/tests/_crafter_preview.gd
+++ b/tests/_crafter_preview.gd
@@ -31,9 +31,9 @@ func _ready() -> void:
 		b.position = Vector2(-240.0 + float(i % 3) * 240.0, -105.0 + float(i / 3) * 215.0)
 		add_child(b)
 		if cell.has("phase"):
-			b.set_process(false)
-			b.anim_time = float(cell.phase) * b.CYCLE
-			b.apply_animation()
+			b.visual.set_process(false)
+			b.visual.anim_time = float(cell.phase) * b.visual.CYCLE
+			b.visual.apply_animation()
 
 	var cam: Camera2D = Camera2D.new()
 	cam.zoom = Vector2(1.65, 1.65)
diff --git a/tests/_gas_surface_preview.gd b/tests/_gas_surface_preview.gd
index ba68e1c..5dafbe5 100644
--- a/tests/_gas_surface_preview.gd
+++ b/tests/_gas_surface_preview.gd
@@ -3,7 +3,7 @@ extends Node2D
 
 func _ready() -> void:
 	GameState.planet_name = "Violet Tempest"
-	GameState.planet_type = "gas_giant"
+	GameState.planet_definition_id = "gas_giant"
 	GameState.surviving_ship_count = 3
 	GameState.rocks = 128
 	GameState.gas = 46
diff --git a/tests/test_animation_continuity.gd b/tests/test_animation_continuity.gd
index d373a25..3919aa6 100644
--- a/tests/test_animation_continuity.gd
+++ b/tests/test_animation_continuity.gd
@@ -53,7 +53,7 @@ func _process(delta: float) -> bool:
 			var ship: Node2D = null
 			for b in field.spawned:
 				if is_instance_valid(b) and b.building_type == GameState.BUILDING_MOTHERSHIP:
-					ship = b
+					ship = b.visual
 			if ship == null:
 				print("TEST_ANIMATION_CONTINUITY: FAIL (mothership never spawned)")
 				quit(1)
diff --git a/tests/test_build_info_popup.gd b/tests/test_build_info_popup.gd
index ef1d708..c67d45c 100644
--- a/tests/test_build_info_popup.gd
+++ b/tests/test_build_info_popup.gd
@@ -28,9 +28,9 @@ var elapsed: float = 0.0
 # Extractor is excluded: it needs a planet underneath, which
 # test_extractor_building covers in full.
 const OPTIONS: Array = [
-	{"press": "_on_place_mothership", "type": "mothership", "title": "Mothership"},
-	{"press": "_on_place_crafter", "type": "ship_crafter", "title": "Ship Crafter"},
-	{"press": "_on_place_command_center", "type": "command_center", "title": "Command Center"},
+	{"type": "mothership", "title": "Mothership"},
+	{"type": "ship_crafter", "title": "Ship Crafter"},
+	{"type": "command_center", "title": "Command Center"},
 ]
 
 
@@ -84,7 +84,7 @@ func _process(delta: float) -> bool:
 				var built_before: int = _count(type)
 
 				controller._on_build_pressed()
-				controller.call(option.press)
+				controller._show_building_info(type)
 
 				var informed: bool = popup.visible \
 					and title.text == option.title \
@@ -111,7 +111,7 @@ func _process(delta: float) -> bool:
 
 				# --- reopening and confirming builds it ------------------
 				controller._on_build_pressed()
-				controller.call(option.press)
+				controller._show_building_info(type)
 				controller._confirm_build()
 				var built: bool = _count(type) == built_before + 1
 				var charged: bool = game_state.rocks == rocks_before - expected_cost
diff --git a/tests/test_building_composition.gd b/tests/test_building_composition.gd
new file mode 100644
index 0000000..7cadf5d
--- /dev/null
+++ b/tests/test_building_composition.gd
@@ -0,0 +1,35 @@
+extends SceneTree
+
+const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
+
+
+func _initialize() -> void:
+	var scene: PackedScene = load("res://Building.tscn")
+	for definition in BUILDING_DEFINITIONS.all():
+		if definition.placement_mode != "space":
+			continue
+		var building: Node2D = scene.instantiate()
+		building.definition_id = definition.definition_id
+		building._ready()
+		if building.definition == null \
+				or building.definition.definition_id != definition.definition_id \
+				or building.visual == null:
+			_fail("%s did not compose its definition and visual (resolved=%s visual=%s)" % [
+				definition.definition_id,
+				"null" if building.definition == null else building.definition.definition_id,
+				building.visual,
+			])
+			return
+		var provider: Node = building.visual.get_node_or_null("ActionProvider")
+		if provider == null or not provider.actions.has("transfer"):
+			_fail("%s has no composed action provider" % definition.definition_id)
+			return
+		building.free()
+
+	print("TEST_BUILDING_COMPOSITION: PASS")
+	quit(0)
+
+
+func _fail(message: String) -> void:
+	print("TEST_BUILDING_COMPOSITION: FAIL (%s)" % message)
+	quit(1)
diff --git a/tests/test_building_composition.gd.uid b/tests/test_building_composition.gd.uid
new file mode 100644
index 0000000..f74b39a
--- /dev/null
+++ b/tests/test_building_composition.gd.uid
@@ -0,0 +1 @@
+uid://bljnijxm3n20e
diff --git a/tests/test_building_redraw_cost.gd b/tests/test_building_redraw_cost.gd
index c083754..1c81451 100644
--- a/tests/test_building_redraw_cost.gd
+++ b/tests/test_building_redraw_cost.gd
@@ -61,11 +61,11 @@ func _process(delta: float) -> bool:
 					continue
 				match b.building_type:
 					GameState.BUILDING_SHIP_CRAFTER:
-						crafter = b
+						crafter = b.visual
 					GameState.BUILDING_MOTHERSHIP:
-						mothership = b
+						mothership = b.visual
 					GameState.BUILDING_COMMAND_CENTER:
-						command = b
+						command = b.visual
 			if crafter == null or mothership == null or command == null:
 				print("TEST_BUILDING_REDRAW_COST: FAIL (buildings never spawned)")
 				quit(1)
@@ -88,7 +88,7 @@ func _process(delta: float) -> bool:
 			for b in [crafter, mothership, command]:
 				if b.draw_count != 1:
 					print("TEST_BUILDING_REDRAW_COST: FAIL (%s redrew its geometry %d times)" % [
-						b.building_type, b.draw_count
+						b.name, b.draw_count
 					])
 					quit(1)
 					return true
diff --git a/tests/test_crafter_animation.gd b/tests/test_crafter_animation.gd
index 7ddab14..9b5d57e 100644
--- a/tests/test_crafter_animation.gd
+++ b/tests/test_crafter_animation.gd
@@ -57,16 +57,19 @@ func _process(delta: float) -> bool:
 			# Spawning is deferred, so give the tree a frame to attach them.
 			if elapsed < 0.2:
 				return false
-			crafter = _find(GameState.BUILDING_SHIP_CRAFTER)
-			if crafter == null:
+			var crafter_building: Node2D = _find(GameState.BUILDING_SHIP_CRAFTER)
+			if crafter_building == null:
 				print("TEST_CRAFTER_ANIMATION: FAIL (crafter never spawned)")
 				quit(1)
 				return true
+			crafter = crafter_building.visual
 
 			var animated: bool = crafter.is_processing()
-			var mothership: Node2D = _find(GameState.BUILDING_MOTHERSHIP)
+			var mothership_building: Node2D = _find(GameState.BUILDING_MOTHERSHIP)
+			var mothership: Node2D = mothership_building.visual if mothership_building != null else null
 			var mothership_animates: bool = mothership != null and mothership.is_processing()
-			var command: Node2D = _find(GameState.BUILDING_COMMAND_CENTER)
+			var command_building: Node2D = _find(GameState.BUILDING_COMMAND_CENTER)
+			var command: Node2D = command_building.visual if command_building != null else null
 			var command_static: bool = command != null and not command.is_processing()
 			print("crafter animates=%s mothership animates=%s command centre static=%s" % [
 				animated, mothership_animates, command_static
diff --git a/tests/test_extractor_building.gd b/tests/test_extractor_building.gd
index 13b2567..0a4b769 100644
--- a/tests/test_extractor_building.gd
+++ b/tests/test_extractor_building.gd
@@ -69,7 +69,7 @@ func _process(delta: float) -> bool:
 				print("TEST_EXTRACTOR_BUILDING: FAIL (enabled with no planet in reach)")
 				quit(1)
 				return true
-			controller._on_place_extractor()
+			controller._show_building_info(GameState.BUILDING_EXTRACTOR)
 			var explained: bool = popup.visible and "planet" in popup.get_node("Panel/MessageLabel").text.to_lower()
 			var offered: bool = popup.get_node("Panel/BuildButton").visible
 			print("no planet: greyed=%s popup_shown=%s confirm_offered=%s" % [
@@ -118,7 +118,7 @@ func _process(delta: float) -> bool:
 				return true
 
 			var rocks_before: int = game_state.rocks
-			controller._on_place_extractor()
+			controller._show_building_info(GameState.BUILDING_EXTRACTOR)
 			var planet_field2: Node = main_scene.get_node("PlanetField")
 			var planet2: Node2D = planet_field2.populated_chunks[target_chunk][0]
 
@@ -148,7 +148,7 @@ func _process(delta: float) -> bool:
 			# A second one on the same planet must be refused, not charged.
 			var rocks_now: int = game_state.rocks
 			controller._on_build_pressed()
-			controller._on_place_extractor()
+			controller._show_building_info(GameState.BUILDING_EXTRACTOR)
 			var re_offered: bool = popup.get_node("Panel/BuildButton").visible
 			controller._confirm_build()   # must do nothing even if pressed
 			var still_one: bool = game_state.extractors.size() == 1 and not re_offered
diff --git a/tests/test_gas_system.gd b/tests/test_gas_system.gd
index 898e43d..94edc1d 100644
--- a/tests/test_gas_system.gd
+++ b/tests/test_gas_system.gd
@@ -27,8 +27,7 @@ func _process(delta: float) -> bool:
 			return _fail("nearby gas giant chunk does not contain a planet")
 		if WorldGen.biome_at_chunk(nearby_chunk) != WorldGen.Biome.SPACE:
 			return _fail("nearby gas giant is not in the normal space biome")
-		if String(nearby_data.get("planet_type", "")) != "gas_giant" \
-				or String(nearby_data.get("resource_type", "")) != "gas":
+		if String(nearby_data.get("definition_id", "")) != "gas_giant":
 			return _fail("nearby guaranteed planet is not a gas source")
 		if nearby_position.length() > WorldGen.CHUNK_SIZE * 2.0:
 			return _fail("nearby gas giant spawned too far away: %s" % nearby_position)
@@ -36,34 +35,49 @@ func _process(delta: float) -> bool:
 		# Gas surfaces have vents only: no deferred ore pickups, and the vent
 		# emission advances continuously so the source visibly looks active.
 		game_state.planet_name = "Gas Test"
-		game_state.planet_type = "gas_giant"
+		game_state.planet_definition_id = "gas_giant"
 		var surface: Node = load("res://PlanetSurface.tscn").instantiate()
 		root.add_child(surface)
-		var rock_field: Node = surface.get_node("RockField")
-		var gas_field: Node = surface.get_node("GasVentField")
-		if not rock_field.rocks.is_empty() or rock_field.is_processing():
+		var gas_field: Node = surface.get_node("SurfaceFeatures/ResourceProvider")
+		if gas_field.get_script() != load("res://GasVentField.gd"):
 			surface.free()
-			return _fail("gas surface spawned or continued processing ore rocks")
+			return _fail("gas surface did not compose the gas feature scene")
+		if surface.get_node_or_null("RockField") != null:
+			surface.free()
+			return _fail("gas surface tree contains an ore producer")
 		gas_field._process(0.5)
 		if gas_field.emission_phase <= 0.0:
 			surface.free()
 			return _fail("gas-source emission animation did not advance")
 		surface.free()
 
+		game_state.planet_definition_id = "rocky"
+		var rocky_surface: Node = load("res://PlanetSurface.tscn").instantiate()
+		root.add_child(rocky_surface)
+		var rocky_features: Node = rocky_surface.get_node("SurfaceFeatures/ResourceProvider")
+		if rocky_features.get_script() != load("res://RockField.gd"):
+			rocky_surface.free()
+			return _fail("rocky surface did not compose the ore feature scene")
+		if rocky_surface.get_node_or_null("GasVentField") != null:
+			rocky_surface.free()
+			return _fail("rocky surface tree contains a gas producer")
+		rocky_surface.free()
+
 		var found_giant: bool = false
 		for x in range(-12, 13):
 			for y in range(-12, 13):
 				var data: Dictionary = WorldGen.planet_data_at_chunk(Vector2i(x, y))
-				if String(data.get("planet_type", "")) == "gas_giant":
-					found_giant = String(data.get("resource_type", "")) == "gas"
+				if String(data.get("definition_id", "")) == "gas_giant":
+					found_giant = true
 					break
 			if found_giant:
 				break
 		if not found_giant:
 			return _fail("world generation produced no deterministic gas giant")
 		var giant: Node2D = load("res://Planet.tscn").instantiate()
-		giant.planet_type = "gas_giant"
-		giant._process(0.5)
+		giant.definition_id = "gas_giant"
+		root.add_child(giant)
+		giant.visual._process(0.5)
 		if giant.gas_phase <= 0.0:
 			return _fail("gas giant animation did not advance")
 		giant.free()
diff --git a/tests/test_generic_inventory.gd b/tests/test_generic_inventory.gd
new file mode 100644
index 0000000..9e9418c
--- /dev/null
+++ b/tests/test_generic_inventory.gd
@@ -0,0 +1,48 @@
+extends SceneTree
+
+const INVENTORY = preload("res://Inventory.gd")
+const TEST_RESOURCE: String = "crystal"
+
+
+func _initialize() -> void:
+	var game_state: Node = root.get_node("GameState")
+	game_state.buildings.clear()
+	game_state.bank_inventory.set_amount(TEST_RESOURCE, 40)
+	game_state.fleet_inventory.set_amount(TEST_RESOURCE, 0)
+
+	var mothership_id: int = game_state.add_building(GameState.BUILDING_MOTHERSHIP, Vector2.ZERO)
+	var crafter_id: int = game_state.add_building(GameState.BUILDING_SHIP_CRAFTER, Vector2(100, 0))
+	if game_state.transfer_resource_to_fleet(mothership_id, TEST_RESOURCE, 15) != 15:
+		return _fail("third resource could not move from bank to fleet")
+	if game_state.transfer_resource_to_building(crafter_id, TEST_RESOURCE, 9) != 9:
+		return _fail("third resource could not move from fleet to building")
+	if game_state.transfer_resource_to_fleet(crafter_id, TEST_RESOURCE, 4) != 4:
+		return _fail("third resource could not move back out of building")
+	if game_state.banked_resource(TEST_RESOURCE) != 25 \
+			or game_state.fleet_resource(TEST_RESOURCE) != 10 \
+			or game_state.building_resource(crafter_id, TEST_RESOURCE) != 5:
+		return _fail("third-resource amounts were not conserved")
+
+	var limited: RefCounted = INVENTORY.new({}, 10)
+	limited.resource_capacities[TEST_RESOURCE] = 6
+	if limited.deposit(TEST_RESOURCE, 99) != 6 or limited.deposit("water", 99) != 4:
+		return _fail("total or per-resource capacity was not enforced")
+
+	var legacy_id: int = game_state.next_building_id
+	game_state.next_building_id += 1
+	game_state.buildings.append({"id": legacy_id, "type": GameState.BUILDING_SHIP_CRAFTER,
+		"position": Vector2.ZERO, "stock": 7, "gas_stock": 3, "orders": []})
+	if game_state.building_resource(legacy_id, GameState.RESOURCE_ORE) != 7 \
+			or game_state.building_resource(legacy_id, GameState.RESOURCE_GAS) != 3:
+		return _fail("legacy building stock was not migrated")
+	var migrated: Dictionary = game_state.find_building(legacy_id)
+	if migrated.has("stock") or migrated.has("gas_stock") or not migrated.has("inventory"):
+		return _fail("legacy fields remained after migration")
+
+	print("TEST_GENERIC_INVENTORY: PASS")
+	quit(0)
+
+
+func _fail(message: String) -> void:
+	print("TEST_GENERIC_INVENTORY: FAIL (%s)" % message)
+	quit(1)
diff --git a/tests/test_generic_inventory.gd.uid b/tests/test_generic_inventory.gd.uid
new file mode 100644
index 0000000..d8972c6
--- /dev/null
+++ b/tests/test_generic_inventory.gd.uid
@@ -0,0 +1 @@
+uid://53pexhmp3ns0
diff --git a/tests/test_hangar_management.gd b/tests/test_hangar_management.gd
index eb6d399..4de3cac 100644
--- a/tests/test_hangar_management.gd
+++ b/tests/test_hangar_management.gd
@@ -68,6 +68,7 @@ func _process(delta: float) -> bool:
 		# own non-overlapping berths to the right only after expansion.
 		var mothership: Node2D = load("res://Building.tscn").instantiate()
 		mothership.set("building_type", GameState.BUILDING_MOTHERSHIP)
+		mothership._ready()
 		controller.current_building = mothership
 		controller.context_actions_expanded = true
 		controller._layout_context_buttons()
diff --git a/tests/test_manual_supply_route.gd b/tests/test_manual_supply_route.gd
index f8479d1..bfb1f86 100644
--- a/tests/test_manual_supply_route.gd
+++ b/tests/test_manual_supply_route.gd
@@ -42,7 +42,8 @@ const CRAFTER_AT: Vector2 = Vector2(3000.0, 0.0)
 func _total() -> int:
 	var sum: int = game_state.rocks + game_state.fleet_cargo
 	for b in game_state.buildings:
-		sum += int(b.get("stock", 0))
+		if b.type != GameState.BUILDING_MOTHERSHIP:
+			sum += game_state.building_resource(int(b.id), GameState.RESOURCE_ORE)
 	return sum
 
 
diff --git a/tests/test_mothership_replacement.gd b/tests/test_mothership_replacement.gd
index 6ebe817..576f039 100644
--- a/tests/test_mothership_replacement.gd
+++ b/tests/test_mothership_replacement.gd
@@ -67,7 +67,7 @@ func _process(delta: float) -> bool:
 				return false
 			# --- first one: informed, then built -------------------------
 			controller._on_build_pressed()
-			controller._on_place_mothership()
+			controller._show_building_info(GameState.BUILDING_MOTHERSHIP)
 			var first_text: String = popup.get_node("Panel/MessageLabel").text.to_lower()
 			var first_warned: bool = "destroy" in first_text
 			print("first: popup=%s warned=%s built_before_confirm=%d" % [
@@ -86,7 +86,7 @@ func _process(delta: float) -> bool:
 			# --- second: warns, builds nothing ---------------------------
 			_place_fleet(second_pos)
 			controller._on_build_pressed()
-			controller._on_place_mothership()
+			controller._show_building_info(GameState.BUILDING_MOTHERSHIP)
 			var warned: bool = popup.visible and "destroy" in popup.get_node("Panel/MessageLabel").text.to_lower()
 			print("second press: warned=%s motherships=%d" % [warned, _count_motherships()])
 			if not warned or _count_motherships() != 1:
@@ -107,7 +107,7 @@ func _process(delta: float) -> bool:
 
 			# --- confirming replaces -------------------------------------
 			var rocks_before: int = game_state.rocks
-			controller._on_place_mothership()
+			controller._show_building_info(GameState.BUILDING_MOTHERSHIP)
 			controller._confirm_build()
 			var only_one: bool = _count_motherships() == 1
 			var moved: bool = game_state.get_mothership_position().distance_to(second_pos) < 60.0
@@ -124,7 +124,7 @@ func _process(delta: float) -> bool:
 			game_state.rocks = GameState.MOTHERSHIP_COST - 1
 			_place_fleet(Vector2(2500.0, -800.0))
 			controller._on_build_pressed()
-			controller._on_place_mothership()
+			controller._show_building_info(GameState.BUILDING_MOTHERSHIP)
 			# With nothing affordable there is no confirm button to press;
 			# pressing it anyway must still do nothing.
 			var offered: bool = popup.get_node("Panel/BuildButton").visible
diff --git a/tests/test_resource_transfer.gd b/tests/test_resource_transfer.gd
index 7b6a00c..f5035bc 100644
--- a/tests/test_resource_transfer.gd
+++ b/tests/test_resource_transfer.gd
@@ -39,7 +39,7 @@ func _total() -> int:
 	var sum: int = game_state.rocks + game_state.fleet_cargo
 	for b in game_state.buildings:
 		if b.type != GameState.BUILDING_MOTHERSHIP:
-			sum += int(b.get("stock", 0))
+			sum += game_state.building_resource(int(b.id), GameState.RESOURCE_ORE)
 	return sum
 
 
diff --git a/tests/test_resources_and_buildings.gd b/tests/test_resources_and_buildings.gd
index 6069a1b..17c6780 100644
--- a/tests/test_resources_and_buildings.gd
+++ b/tests/test_resources_and_buildings.gd
@@ -38,7 +38,7 @@ func _process(delta: float) -> bool:
 	match stage:
 		0:
 			# --- gather a rock -------------------------------------------
-			scene.get_node("RockField").set_process(false)
+			scene.get_node("SurfaceFeatures/ResourceProvider").set_process(false)
 			rock = load("res://Rock.tscn").instantiate()
 			rock.build_shape(1)
 			# Placed OUTSIDE the pickup shape but inside attract_radius, so
diff --git a/tests/test_skill_tree.gd b/tests/test_skill_tree.gd
index 7b2a887..5c9d21c 100644
--- a/tests/test_skill_tree.gd
+++ b/tests/test_skill_tree.gd
@@ -72,9 +72,9 @@ func _process(delta: float) -> bool:
 			# Since #21 an unresearched structure is not listed at all, rather
 			# than listed and greyed. It is therefore unreachable from the
 			# menu - but the popup must still refuse if something calls
-			# _on_place_crafter() by another route.
+			# the generic definition entry point by another route.
 			var hidden: bool = not scene.get_node("UI/BuildMenu/CrafterButton").visible
-			controller._on_place_crafter()
+			controller._show_building_info(GameState.BUILDING_SHIP_CRAFTER)
 			var offered: bool = popup.get_node("Panel/BuildButton").visible
 			print("locked crafter: hidden_from_menu=%s confirm_offered=%s" % [hidden, offered])
 			if not hidden or offered:
diff --git a/tests/test_transport_hub_building.gd b/tests/test_transport_hub_building.gd
index b2cc4eb..dcb03a6 100644
--- a/tests/test_transport_hub_building.gd
+++ b/tests/test_transport_hub_building.gd
@@ -1,5 +1,7 @@
 extends SceneTree
 
+const BUILDING_DEFINITIONS = preload("res://BuildingDefinitions.gd")
+
 # Headless gameplay test: run with
 #   godot --headless -s res://tests/test_transport_hub_building.gd
 # Forgejo #18 (part 5 of #12): the Transport Hub is a placeable building of
@@ -67,7 +69,7 @@ func _process(delta: float) -> bool:
 			var icons: Dictionary = {}
 			for type in [GameState.BUILDING_MOTHERSHIP, GameState.BUILDING_SHIP_CRAFTER,
 					GameState.BUILDING_COMMAND_CENTER, GameState.BUILDING_TRANSPORT_HUB]:
-				var icon: int = controller._action_icon_for(type)
+				var icon: int = BUILDING_DEFINITIONS.get_definition(type).action_icon
 				if icons.has(icon):
 					print("TEST_TRANSPORT_HUB_BUILDING: FAIL (%s and %s share an icon)" % [type, icons[icon]])
 					quit(1)
@@ -99,7 +101,7 @@ func _process(delta: float) -> bool:
 				return false
 			for b in field.spawned:
 				if is_instance_valid(b) and b.building_type == GameState.BUILDING_TRANSPORT_HUB:
-					hub = b
+					hub = b.visual
 			if hub == null:
 				print("TEST_TRANSPORT_HUB_BUILDING: FAIL (never spawned)")
 				quit(1)
@@ -120,9 +122,9 @@ func _process(delta: float) -> bool:
 			for m in markers:
 				if m.type == GameState.BUILDING_TRANSPORT_HUB:
 					found = true
-					if m.color == map_content.CRAFTER_MARKER_COLOR \
-							or m.color == map_content.MOTHERSHIP_MARKER_COLOR \
-							or m.color == map_content.COMMAND_MARKER_COLOR:
+					if m.color == BUILDING_DEFINITIONS.get_definition(GameState.BUILDING_SHIP_CRAFTER).map_color \
+							or m.color == BUILDING_DEFINITIONS.get_definition(GameState.BUILDING_MOTHERSHIP).map_color \
+							or m.color == BUILDING_DEFINITIONS.get_definition(GameState.BUILDING_COMMAND_CENTER).map_color:
 						print("TEST_TRANSPORT_HUB_BUILDING: FAIL (map marker reuses another building's colour)")
 						quit(1)
 						return true
diff --git a/tests/test_transporter_supply.gd b/tests/test_transporter_supply.gd
index 8130e16..ca9dcbb 100644
--- a/tests/test_transporter_supply.gd
+++ b/tests/test_transporter_supply.gd
@@ -43,7 +43,8 @@ const CRAFTER_AT: Vector2 = Vector2(900.0, -300.0)
 func _total() -> int:
 	var sum: int = game_state.rocks + game_state.fleet_cargo
 	for b in game_state.buildings:
-		sum += int(b.get("stock", 0))
+		if b.type != GameState.BUILDING_MOTHERSHIP:
+			sum += game_state.building_resource(int(b.id), GameState.RESOURCE_ORE)
 	for t in game_state.transporters:
 		sum += int(t.get("carrying", 0))
 	# Ore inside a build that has STARTED but not finished (#23). It has left
diff --git a/tests/test_vessel_composition.gd b/tests/test_vessel_composition.gd
new file mode 100644
index 0000000..f25f447
--- /dev/null
+++ b/tests/test_vessel_composition.gd
@@ -0,0 +1,50 @@
+extends SceneTree
+
+const VESSEL_DEFINITIONS = preload("res://VesselDefinitions.gd")
+
+var ships: Array = []
+var elapsed: float = 0.0
+var game_state: Node
+
+
+func _initialize() -> void:
+	game_state = root.get_node("GameState")
+	var scene: PackedScene = load("res://Ship.tscn")
+	for definition in VESSEL_DEFINITIONS.all():
+		var ship: Area2D = scene.instantiate()
+		ship.vessel_type = definition.definition_id
+		root.add_child(ship)
+		ships.append(ship)
+
+
+func _process(delta: float) -> bool:
+	elapsed += delta
+	if elapsed < 0.1:
+		return false
+	var definitions: Array = VESSEL_DEFINITIONS.all()
+	if ships.size() != definitions.size():
+		return _fail("catalog and composed fleet differ in size")
+	for i in range(definitions.size()):
+		var definition: Resource = definitions[i]
+		var ship: Node = ships[i]
+		if ship.definition == null or ship.definition.definition_id != definition.definition_id:
+			return _fail("%s did not resolve its definition" % definition.definition_id)
+		for capability in definition.capabilities:
+			if not ship.has_capability(capability):
+				return _fail("%s did not compose %s" % [definition.definition_id, capability])
+		if game_state.product_cost(definition.definition_id) != definition.build_cost \
+				or game_state.vessel_name(definition.definition_id) != definition.display_name:
+			return _fail("%s metadata did not come from its definition" % definition.definition_id)
+	if ships[0].has_capability("shield") or not ships[1].has_capability("shield"):
+		return _fail("shield behavior is not controlled by component presence")
+	if ships[2].has_capability("weapon") or not ships[2].has_capability("transport"):
+		return _fail("transporter capabilities were composed incorrectly")
+	print("TEST_VESSEL_COMPOSITION: PASS")
+	quit(0)
+	return true
+
+
+func _fail(message: String) -> bool:
+	print("TEST_VESSEL_COMPOSITION: FAIL (%s)" % message)
+	quit(1)
+	return true
diff --git a/tests/test_vessel_composition.gd.uid b/tests/test_vessel_composition.gd.uid
new file mode 100644
index 0000000..d490e27
--- /dev/null
+++ b/tests/test_vessel_composition.gd.uid
@@ -0,0 +1 @@
+uid://cq73poxld1e35